Method for selective hydrogenation of ethylene produced by ethane cracking

Abstract

A selective hydrogenation method for ethane cracking to olefins involves selectively hydrogenating the ethylene feedstock from the top of an ethane stripper to remove acetylene. Reaction conditions: inlet temperature 50℃~95℃, pressure 1.5~3.0MPa, space velocity 8000~14000h⁻¹ ‑1 The preferred reaction conditions are: reactor inlet temperature 60℃~90℃, reaction pressure 2.0~2.5MPa, and space velocity 9000~12000h⁻¹. ‑1 The catalyst support is alumina or mainly alumina, and has a bimodal pore structure. The specific surface area of ​​the catalyst is 3–16 m². 2 The catalyst contains at least Pd, Fe, Ni, and Cu, with Pd supported in both microemulsion and solution formats. Ni and Cu are supported in microemulsion, while Fe is supported in solution. The solution-supported Pd and Fe are primarily located in the 56–75 nm micropores, while the microemulsion-supported Ni, Cu, and Pd are mainly distributed in the 300–650 nm macropores of the support. This alkyne removal method exhibits excellent catalytic performance and anti-coking properties, with low "green oil" formation.

Description

Technical Field

[0001] This invention relates to a method for selective hydrogenation of ethane cracking to olefins, and more particularly to a method for hydrogenating trace amounts of acetylene contained in the overhead feed of an ethane cracking deethaner to olefins into ethylene using a Pd-Fe-Ni-Cu catalyst. Background Technology

[0002] Ethylene, propylene, and other low-carbon olefins are important basic chemical raw materials. With the development of my country's national economy, especially the development of modern chemical industry, the demand for low-carbon olefins is increasing, and the supply-demand imbalance is becoming increasingly prominent. To date, the main route for producing ethylene, propylene, and other low-carbon olefins is still through the catalytic cracking and pyrolysis of naphtha and light diesel oil (both derived from petroleum). However, the raw material resources such as naphtha and light diesel oil used in ethylene production are facing increasingly severe shortages. Furthermore, in recent years, my country's crude oil imports have accounted for about half of its total processing volume, and the import ratio of polyolefin products using ethylene and propylene as raw materials will continue to remain quite high. Therefore, the development of technologies for producing low-carbon olefins from non-petroleum resources is attracting increasing attention.

[0003] Currently, there are three main feedstocks for ethylene production both domestically and internationally: petroleum, coal, and ethane. The petroleum route utilizes naphtha cracking, which not only has a heavy feedstock structure and high production costs but also a high dependence on petroleum resources. Ethylene production in China primarily uses naphtha as a feedstock, resulting in higher costs than ethylene production in North America and the Middle East, which uses inexpensive ethane. Compared to naphtha, ethane cracking yields lower amounts of methane, propylene, and butadiene, but a higher ethylene yield. Among all traditional cracking feedstocks, ethane cracking yields the highest ethylene output and the lowest methane output, meaning that the energy consumption of the separation unit is relatively low. Methane, typically used as fuel, has the lowest economic value. Therefore, ethane is the highest-quality cracking feedstock for ethylene production, offering advantages such as high ethylene yield, short process flow, lower equipment investment, and less pollution.

[0004] Basic principle of ethane cracking:

[0005] Steam cracking is the most widely used method for producing ethylene. The main reaction is relatively simple [as shown in formula (1)], where ethane undergoes a dehydrogenation reaction at 850℃ and 70kPa to produce ethylene, with hydrogen as a byproduct. Other major products during the reaction include methane, acetylene, propylene, propane, butadiene, and other hydrocarbons.

[0006] C2H6→C2H4+H2 (1)

[0007] 2C2H6→C3H8+CH4 (2)

[0008] C3H8→C3H6+H2 (3)

[0009] C3H8→C2H4+CH4 (4)

[0010] C3H6→C2H2+CH4 (5)

[0011] C2H2 + C2H4 → C4H6 (6)

[0012] 2C2H6→C2H4+2CH4 (7)

[0013] C2H6 + C2H4 → C3H6 + CH4 (8)

[0014] After the cracked gas is washed with alkali and dehydrated, the ethylene feed from the top of the deethaner still contains 0.15-0.3% acetylene. It needs to be selectively hydrogenated to remove the acetylene to below 1 ppm before it can be used as a raw material for the production of polymer-grade ethylene.

[0015] Currently, the selective removal of trace amounts of acetylene from ethylene feedstock in ethane cracking to olefins plants mainly employs a two-stage reactor series process (feedstock composition is shown in Table 2). The reaction pressure is 1.5–3.0 MPa, and the space velocity is 6000–14000 h⁻¹. -1 The inlet temperature is 50℃~90℃.

[0016] Table 2. Composition of feedstock for ethane cracking to olefins C2 hydrogenation

[0017] Hydrogenation feedstock <![CDATA[H2]]> <![CDATA[C2H2]]> <![CDATA[C2H4]]> <![CDATA[C2H6]]> <![CDATA[CH4]]> CO Content (Φ%) 25～45 0.15～0.3 30～45 5.0～20.0 10～30 0.02～0.2

[0018] Selective hydrogenation catalysts for alkynes and dienes are obtained by supporting noble metals such as palladium on porous inorganic material supports (US4762956). To increase catalyst selectivity and reduce catalyst deactivation caused by green oil produced during oligomerization reactions during hydrogenation, existing technologies employ methods such as adding Group IB elements as co-catalytic components: Pd-Au (US4490481), Pd-Ag (US4404124), Pd-Cu (US3912789), or adding alkali metals or alkaline earth metals (US5488024), etc. Supports used include alumina, silica (US5856262), and honeycomb lapis lazuli (CN1176291). Patent US4404124 describes a selective hydrogenation catalyst with a palladium shell layer distribution of the active component prepared by a stepwise impregnation method. This catalyst can be applied to the selective hydrogenation of C2 and C3 fractions to eliminate acetylene from ethylene and propyne and propadiene from propylene. US5587348 describes a high-performance C2 hydrogenation catalyst prepared by using alumina as a support, adjusting the interaction between silver and palladium co-catalysts, and adding alkali metals and chemically bonded fluorine. This catalyst features reduced green oil formation, improved ethylene selectivity, and reduced oxygen-containing compound formation. US5519566 discloses a wet reduction method for preparing silver and palladium catalysts by adding organic or inorganic reducing agents to the impregnation solution to prepare a silver and palladium bicomponent selective hydrogenation catalyst. CN105732266A discloses a Pd-Ag catalyst using Al2O3 or a mixture of Al2O3 and other oxides as a support. The catalyst contains 0.025–0.060% Pd and 0.05–0.4% Ag by mass (100%). Patents such as CN102898266A, CN107970927A, CN105732266A, and CN105732271A all utilize Pd catalysts.

[0019] The above-mentioned traditional C2 hydrogenation catalysts are all prepared by impregnation method, and their active phase is a Pd / Ag bimetallic catalyst. This method has the following disadvantages: (1) Due to the influence of the pore structure of the support, the dispersion of the active components cannot be precisely controlled and has strong randomness. (2) Due to the influence of the surface tension and solvation effect of the impregnation liquid, the precursor of the metal active component is deposited on the surface of the support in the form of aggregates and cannot form a uniform distribution. (3) C2 hydrogenation requires high catalyst selectivity. The traditional preparation method promotes the role of Ag promoter by increasing the amount of Ag, which leads to the obstruction of hydrogen transfer, the increased possibility of oligomerization reaction, and the increase of green oil generation, which affects the catalyst life. (4) The catalyst has a high Pd content and is expensive. In addition, the occurrence of the above four phenomena can easily lead to poor dispersion of the metal active component, low reaction selectivity, and high green oil generation, which in turn affects the overall performance of the catalyst.

[0020] CN201110086174.0 describes a method that adsorbs specific polymeric compounds onto a support, forming a polymeric coating of a certain thickness on the support surface. The reaction of functionalized compounds with the polymer imparts functional groups that can complex with the active component. The active component undergoes a complexation reaction on these functional groups on the support surface, ensuring the ordered and highly dispersed nature of the active component. However, this patented method involves adsorbing specific polymeric compounds onto the support, with the polymer undergoing chemical adsorption via the hydroxyl groups of alumina. The amount of polymeric compound adsorbed by the support is limited by the number of hydroxyl groups in the alumina. Furthermore, the complexation between the functionalized polymer and Pd is weak, sometimes resulting in insufficient loading of the active component, leaving some active component residue in the impregnation solution, thus increasing catalyst costs.

[0021] To improve the anti-coking performance of catalysts and reduce the degree of surface coking, C2 selective hydrogenation catalysts and their preparation methods using bimodal porous supports and microemulsion methods for loading active components have been disclosed in recent years. Patent ZL201310114077.7 discloses a selective hydrogenation catalyst whose support is mainly alumina with a bimodal porous structure, wherein the pore size is less than 50 nm and the macropore size is 60–800 nm. Based on 100% catalyst mass, the catalyst contains 0.01–0.5% Pd in ​​a shell distribution with a thickness of 1–500 μm; and 0.2–5% Ni. The anti-coking component Ni is controlled by microemulsion method, where the microemulsion particle size is larger than the support pore size, so that Ni is mainly distributed in the macropores of the support. Patent ZL201310114079.6 discloses a method for preparing a hydrogenation catalyst, where the catalyst support is mainly alumina with a bimodal porous structure. The catalyst contains two active components, Pd and Ni. During catalyst preparation, the anti-coking component Ni is introduced into the macropores of the support in the form of a microemulsion, while the active component Pd is mainly distributed on the support surface, particularly in the micropores. Patent ZL201310114371.8 discloses a selective hydrogenation method for C2 fractions suitable for pre-propane dehydrogenation processes. This method uses a selective hydrogenation catalyst whose support is alumina or mainly alumina, with a bimodal pore distribution structure, containing two active components, Pd and Ni, with the anti-coking component Ni mainly distributed in the macropores. While this method improves the catalyst's anti-coking performance, the single-component Ni in the macropores of the catalyst support reaches reduction temperatures above 500°C. Reduction at this temperature causes the active component Pd to aggregate, significantly reducing catalyst activity. To compensate for the loss of catalyst activity, the amount of active component needs to be increased, leading to a decrease in catalyst selectivity and a reduction in the utilization rate of the active component.

[0022] CN106927993A discloses a catalyst active component containing at least Fe and Cu. It is believed that adding Cu to the iron-containing active component is more conducive to lowering the activation temperature, promoting the formation and dispersion of the activated phase, and improving catalyst selectivity. Simultaneously, the addition of Cu facilitates the adsorption and activation of alkynes, further enhancing catalyst activity. The calcination temperature is preferably 300℃~400℃; reduction is carried out at 260~330℃.

[0023] In addition, we have developed a series of Fe-based bimetallic acetylene selective hydrogenation and acetylene removal catalysts. Taking the typical CN106928001.B as an example, the acetylene hydrogenation method disclosed in the catalyst contains at least Fe and Cu as active components. Based on 100% catalyst mass, the catalyst contains 1-8% Fe and 0.03-0.3% Cu, with a catalyst specific gravity of 10-200 mg / L. 2 / g, with a pore volume of 0.2–0.63 mL / g. Summary of the Invention

[0024] This invention relates to a selective hydrogenation method, and more particularly to a hydrogenation method for converting trace amounts of acetylene contained in the product of ethane cracking to olefins into ethylene.

[0025] The selective hydrogenation method described in this invention refers to selective hydrogenation in a reactor with two adiabatic beds in series or a reactor with three adiabatic beds in series, preferably with two adiabatic beds in series.

[0026] This invention provides a selective hydrogenation method for ethane cracking to olefins, which selectively hydrogenates the C2 feedstock in ethane cracking to remove acetylene.

[0027] The selective hydrogenation method described in this invention uses a feedstock composition (volume ratio) of H2 25-45%, CO 0.02-0.2%, methane 10-30%, acetylene 0.15-0.3%, and ethylene 30-45%.

[0028] The reactor inlet temperature is 50℃~95℃, the reaction pressure is 1.5~3.0MPa, and the space velocity is 8000~14000h. -1 The preferred reaction conditions are: reactor inlet temperature 60℃~90℃, reaction pressure 2.0~2.8MPa, and space velocity 9000~12000h⁻¹. -1 .

[0029] In the selective hydrogenation method described in this invention, the reduction temperature of the catalyst used is preferably 150–200°C.

[0030] The selective hydrogenation method described in this invention uses alumina or mainly alumina as the catalyst support, which has a bimodal pore distribution structure, and the specific surface area of ​​the catalyst is 3-10 m².2 / g, wherein the pore size of the micropores is 56-75nm and the pore size of the macropores is 300-680nm. The catalyst contains at least Pd, Fe, Ni, and Cu, wherein Pd is supported in both microemulsion and solution modes, Ni and Cu are supported in microemulsion mode, and Fe is supported in solution mode. Based on the mass of the catalyst (100%), the Pd content is 0.008–0.02%, preferably 0.008–0.015%; the Fe content is 0.7–2.3%, preferably 0.8–2.0%; the Ni content is 0.5–8.0%, preferably 2.0–5.8%; the weight ratio of Cu to Ni is 0.1–0.9, preferably 0.3–0.8; the Pd content of the microemulsion-loaded catalyst is 1 / 15–1 / 4, preferably 1 / 10–1 / 5, of the Pd content of the solution-loaded catalyst; wherein, the Ni, Cu, and Pd of the microemulsion-loaded catalyst are mainly distributed in the macropores of the support (300–680 nm).

[0031] The selective hydrogenation method of the present invention uses a catalyst containing at least Fe, Pd, Ni, and Cu. The selective hydrogenation reaction of alkynes occurs at the reaction center composed of Fe and Pd, where Fe is the main active component of the catalyst, and its role is to adsorb and activate acetylene, thereby catalyzing the selective hydrogenation of acetylene. The small amount of Pd loaded in the solution is a co-active component of the catalyst, which is beneficial to the rapid dissociation of hydrogen, thereby improving the activity of the catalyst.

[0032] In the selective hydrogenation method described in this invention, the selective hydrogenation reaction of acetylene mainly occurs at the main active centers composed of Pd and Fe loaded in the solution; Ni and Cu are impregnated in the macropores of the support in the form of microemulsions, and the green oil generated in the reaction undergoes saturated hydrogenation on the active centers composed of Cu and Ni.

[0033] The role of Cu is to form Ni / Cu alloy during the calcination process, effectively reduce the reduction temperature of nickel during the reduction process, reduce the polymerization of Fe and Pd at high temperatures, improve the dispersion of the main active components, and at the same time modulate the saturated hydrogenation reaction performance of Ni in macropores.

[0034] For hydrogenation reactions, the catalyst generally needs to be reduced before application to ensure the active component exists in a metallic state, thus enabling the catalyst to exhibit hydrogenation activity. This is because activation during catalyst preparation is a high-temperature calcination process, during which metal salts decompose into metal oxides, which then form clusters, typically nanoscale. Different oxides, due to their varying chemical properties, require reduction at different temperatures. However, for nanoscale metals, around 200°C is a crucial critical temperature; exceeding this temperature leads to significant metal particle aggregation. Therefore, lowering the reduction temperature of the active component is of paramount importance for hydrogenation catalysts.

[0035] The solution to catalyst coking in this invention is as follows:

[0036] Selective hydrogenation of alkynes occurs at the main active centers of the catalyst, such as Fe and Pd. Large molecules, such as the green oil produced in the reaction, easily enter the macropores of the catalyst. Within these macropores, a Ni / Cu component is loaded, where Ni possesses saturated hydrogenation capabilities. The green oil component undergoes saturated hydrogenation at the Ni / Cu active centers. Because the double bonds are hydrogenated to saturation, the green oil component cannot undergo polymerization or its polymerization rate is significantly reduced. Its chain growth reaction is terminated or delayed, preventing the formation of large molecular weight fused-ring compounds. This prevents the green oil from being carried out of the reactor by the surrounding material, thus greatly reducing coking on the catalyst surface and significantly extending its service life.

[0037] The selective hydrogenation method described in this invention uses Fe as the main active component. However, compared with the disclosed iron-based acetylene hydrogenation catalysts, the Fe content is lower, even less than 1 wt% of the catalyst, and the reduction temperature is also significantly reduced, allowing the catalyst to be reduced at temperatures below 200°C.

[0038] In the selective hydrogenation method described in this invention, Pd loaded in solution is used as a co-activating component to increase the activity of the catalyst and modulate the selectivity of the catalyst. Compared with the disclosed noble metal Pd-based acetylene hydrogenation catalysts, the Pd content is significantly reduced, even by more than 50%.

[0039] The method for controlling the positioning of the Ni / Cu alloy within the macropores of the catalyst in this invention involves loading Ni / Cu in the form of a microemulsion. The particle size of the microemulsion is larger than the micropore diameter of the support but smaller than the maximum pore diameter of the macropores. The nickel and copper metal salts, contained within the microemulsion, have difficulty entering the smaller pores of the support due to steric hindrance, and therefore primarily enter the macropores of the support.

[0040] In this invention, loading Cu and Ni together can lower the reduction temperature of Ni. This is because to completely reduce NiO alone, a reduction temperature of 450-500°C is generally required. At this temperature, Pd agglomeration will occur. However, after forming a Cu / Ni alloy, its reduction temperature can be reduced by more than 100°C compared to the reduction temperature of pure Ni, reaching 350°C, thereby alleviating the agglomeration of Pd during the reduction process.

[0041] In this invention, a small amount of Pd loaded in a microemulsion on the surface of the Ni / Cu alloy can further reduce the reduction temperature of Ni to below 200°C, with a minimum of 150°C.

[0042] In this invention, during the solution-based loading of palladium and iron, the solution containing palladium and iron enters the pores more quickly due to the siphon effect of the pores. Since palladium and iron exist in ionic form, these ions can form chemical bonds with the hydroxyl groups on the support surface, allowing for rapid targeting of palladium and iron. Therefore, the faster the solution enters the pores, the faster the loading speed. Thus, in the process of impregnating Pd and Fe using the solution method, it is easier to load them into the pores.

[0043] This invention is not particularly limited to loading Ni, Cu, and Pd in ​​a microemulsion manner. As long as a microemulsion particle size greater than 75 nm and less than 680 nm can be formed, Ni, Cu, and Pd can be distributed in the macropores of the carrier.

[0044] The preferred preparation process of the catalyst of the present invention specifically includes the following steps:

[0045] (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, with the microemulsion particle size controlled to be greater than 75 nm and less than 680 nm. The conditions for preparing the microemulsion provided in this invention are as follows: an oil phase, surfactant, and co-surfactant are added, with the weight ratio of surfactant to co-surfactant being 1.0–1.2, the weight ratio of aqueous phase to oil phase being 4.5–5.8, and the weight ratio of surfactant to oil phase being 0.1–0.35. The support is added to the prepared microemulsion and impregnated for 0.5–4 hours, and the remaining liquid is filtered off. The mixture is dried at 60–120 °C for 1–6 hours and calcined at 300–600 °C for 2–8 hours to obtain a semi-finished catalyst A.

[0046] (2) Fe loading was carried out by saturation impregnation, that is, the Fe salt solution was prepared to have a saturation water absorption rate of 80-110% of that of the support. The pH was adjusted to 1-5, and the semi-finished catalyst A, after being loaded with Fe, was calcined at 500-550℃ for 4-6 hours to obtain semi-finished catalyst B.

[0047] (3) Dissolve the precursor salt of Pd in ​​water, adjust the pH to 1.5-2.5, add the semi-finished catalyst B to the salt solution of Pd, impregnate and adsorb for 0.5-4 hours, dry at 100-120℃ for 1-4 hours, and calcine at 400-550℃ for 2-6 hours to obtain the semi-finished catalyst C.

[0048] (4) Dissolve the Pd precursor salt in water, add the oil phase, surfactant, and co-surfactant, and stir thoroughly to form a microemulsion, controlling the microemulsion particle size to be greater than 75 nm and less than 680 nm. The conditions for preparing the microemulsion provided in this invention are: adding the oil phase, surfactant, and co-surfactant, with a surfactant-to-co-surfactant weight ratio of 1.0–1.2, an aqueous phase-to-oil phase weight ratio of 4.5–5.8, and a surfactant-to-oil phase weight ratio of 0.1–0.35. Add the semi-finished catalyst C to the prepared microemulsion and impregnate for 0.5–4 hours, then filter out the remaining liquid. Dry at 60–120°C for 1–6 hours, and calcine at 300–600°C for 2–8 hours. The desired catalyst is obtained.

[0049] In the above preparation steps, steps (1) and (2) can be interchanged. The loading order of Fe and Pd in ​​the solution is not particularly limited. The preferred order is that the loading of Fe in the solution precedes the loading of Pd in ​​the solution. The loading of Ni and Cu in the microemulsion must precede the loading of Pd in ​​the microemulsion.

[0050] The support in step (1) above is alumina or mainly alumina, and the Al2O3 crystal form is preferably α, θ or a mixture thereof. The alumina content in the catalyst support is preferably above 80%, and the support may also contain other metal oxides such as magnesium oxide, titanium oxide, etc.

[0051] The carrier in step (1) above can be spherical, cylindrical, clover-shaped, four-leaf clover-shaped, etc.

[0052] The precursor salts of Pd, Fe, Ni and Cu mentioned in steps (1) and (3) above are soluble salts, which can be their nitrates, chlorides or other soluble salts.

[0053] The surfactants in steps (1) and (4) above are ionic surfactants and / or nonionic surfactants, preferably nonionic surfactants, and more preferably polyethylene glycol octylphenyl ether (Triton X-100) or hexadecyltrimethylammonium bromide (CTAB).

[0054] The oil phase in steps (1) and (4) above is a C6-C8 saturated alkane or cycloalkane, preferably cyclohexane or n-hexane.

[0055] The co-surfactants in steps (1) and (4) above are C4 to C6 alcohols, preferably n-butanol and / or n-pentanol.

[0056] This catalyst exhibits the following characteristics: At the start of the hydrogenation reaction, due to the high hydrogenation activity of palladium and iron, and their predominantly distributed within the micropores, the selective hydrogenation of acetylene primarily occurs within these micropores. As the catalyst's operating time increases, a number of larger molecular weight byproducts are generated on the catalyst surface. These substances, due to their larger molecular size, enter the macropores more frequently and have a longer residence time. Under the action of the nickel catalyst, they undergo double bond hydrogenation reactions to generate saturated hydrocarbons or aromatic hydrocarbons without isolated double bonds, without forming substances with even larger molecular weights.

[0057] Using the selective hydrogenation method of this invention, the reduction temperature of the catalyst can be significantly reduced, down to as low as 150-200°C, reducing the agglomeration of active components during the reduction process. The catalyst prepared by this method has significantly improved initial activity, activity and selectivity compared to traditional catalysts.

[0058] Using the selective hydrogenation method of the present invention, even if the feedstock contains a large amount of heavy fractions and the amount of green oil generated by the catalyst increases significantly, the catalyst activity and selectivity do not show a downward trend. Attached Figure Description

[0059] Figure 1 This is a flow chart of the C2 hydrogenation process for ethane cracking to olefins using a sequential separation process. Detailed Implementation

[0060] Analysis and testing methods:

[0061] Specific surface area: GB / T-5816;

[0062] Hole capacity: GB / T-5816;

[0063] Content of active component in catalyst: atomic absorption spectrometry;

[0064] Microemulsion particle size distribution of Ni / Cu alloy: Dynamic light scattering particle size analyzer, analyzed on M286572 dynamic light scattering analyzer;

[0065] In this embodiment, the conversion rate and selectivity are calculated using the following formula:

[0066] MAPD conversion rate (%) = 100 × ΔMAPD / inlet MAPD content

[0067] Propylene selectivity (%) = 100 × Δpropylene / ΔMAPD

[0068] Example 1

[0069] Carrier: A commercially available bimodal spherical alumina carrier with a diameter of 4 mm was used. 100 g of the carrier was calcined at high temperature for 4 hours. The calcination temperature and carrier properties are shown in Table 3.

[0070] Catalyst preparation:

[0071] (1) Weigh a certain amount of nickel nitrate and copper chloride, dissolve them in deionized water, add a certain amount of cyclohexane, Triton X-100, and n-butanol, and stir thoroughly to form a microemulsion. Impregnate 100g of the carrier into the prepared microemulsion. After impregnation for 1 hour, wash with deionized water until neutral, dry at 120℃ for 2 hours, and calcine at 550℃ for 5 hours. Semi-finished catalyst A is obtained.

[0072] (2) Weigh ferric chloride, prepare a solution with deionized water, immerse catalyst A in the above solution, shake, and after the solution is completely absorbed, dry at 110°C for 3 hours and calcine at 500°C for 4 hours to obtain semi-finished catalyst B.

[0073] (3) Weigh a certain amount of palladium nitrate, dissolve it in deionized water, adjust the pH to 1, add the semi-finished catalyst B to the solution, impregnate and adsorb for 1 hour, dry at 110℃ for 2 hours, and calcine at 380℃ for 6 hours to obtain the semi-finished catalyst C.

[0074] (4) Weigh a certain amount of palladium nitrate and dissolve it in water. Add a certain amount of cyclohexane, Triton X-100, and 6.03 g of n-hexanol and stir thoroughly to form a microemulsion. Add the semi-finished catalyst C to the prepared microemulsion and impregnate for 4 hours. Wash with deionized water until neutral, dry at 90°C for 4 hours, and calcine at 600°C for 2 hours to obtain the finished catalyst.

[0075] The particle size of the microemulsion prepared during the catalyst preparation process and the content of each component in the catalyst are shown in Table 4.

[0076] Before use, place it in a fixed-bed reactor and reduce it for 12 hours at 190°C using a mixed gas with a molar ratio of N2:H2 = 1:1.

[0077] The reduction temperature peaks of the catalysts supported only on Ni / Cu and the catalysts supported on Pb-Ni / Cu as in Example 1 were measured. The reduction peak of the catalyst supported only on Ni / Cu was around 350°C, while the reduction temperature of the catalyst supported on Pb-Ni / Cu was around 150°C.

[0078] Example 2

[0079] Carrier: A commercially available bimodal spherical carrier with a diameter of 4 mm was used, consisting of 90 wt% alumina and 10 wt% titanium oxide. After high-temperature calcination for 4 hours, 100 g of the carrier was weighed. The physical properties of the carrier are shown in Table 3.

[0080] Catalyst preparation:

[0081] (1) Weigh out a certain amount of nickel nitrate and copper chloride, dissolve them in deionized water, add a certain amount of cyclohexane, Triton X-100, and n-hexanol, and stir thoroughly to form a microemulsion. Add the support to the prepared microemulsion and impregnate for 1 hour, then wash with deionized water until neutral, dry at 120°C for 2 hours, and calcine at 550°C for 5 hours. Obtain the semi-finished catalyst A.

[0082] (2) Weigh a certain amount of palladium nitrate and dissolve it in water. Add a certain amount of cyclohexane, Triton X-100, and 6.03 g of n-hexanol and stir thoroughly to form a microemulsion. Add the semi-finished catalyst A to the prepared microemulsion and impregnate for 4 hours. Wash with deionized water until neutral, dry at 90°C for 4 hours, and calcine at 600°C for 2 hours to obtain the semi-finished catalyst B.

[0083] (3) Weigh a certain amount of ferric chloride and dissolve it in deionized water. Immerse the semi-finished catalyst B in the prepared solution, dry it at 110°C for 3 hours, and calcine it at 500°C for 4 hours to obtain the semi-finished catalyst C.

[0084] (4) Weigh a certain amount of palladium nitrate salt and dissolve it in water, adjust the pH to 2, add the semi-finished catalyst C to the salt solution of Pd, impregnate and adsorb for 1 hour, dry at 110℃ for 2 hours, and calcine at 380℃ for 6 hours to obtain the finished catalyst.

[0085] The particle size of the microemulsion prepared during the catalyst preparation process and the content of each component in the catalyst are shown in Table 4.

[0086] Before use, place it in a fixed-bed reactor and reduce it for 12 hours at 180°C using a mixed gas with a molar ratio of N2:H2 = 1:1.

[0087] Example 3

[0088] Carrier: A commercially available bimodal spherical alumina carrier with a diameter of 4 mm was used. After high-temperature calcination for 4 hours, 100 g of the carrier was weighed, and its physical properties are shown in Table 3.

[0089] Catalyst preparation:

[0090] (1) Weigh a certain amount of ferric chloride and dissolve it in deionized water. Immerse the carrier in the prepared solution, dry it at 110°C for 3 hours, and calcine it at 500°C for 4 hours to obtain the semi-finished catalyst A.

[0091] (2) Weigh a certain amount of palladium nitrate salt and dissolve it in water, adjust the pH to 2, add the semi-finished catalyst A into the salt solution of Pd, impregnate and adsorb for 1 hour, dry at 110℃ for 2 hours, and calcine at 380℃ for 6 hours to obtain the semi-finished catalyst B.

[0092] (3) Weigh out a certain amount of nickel nitrate and copper chloride, dissolve them in water, add a certain amount of cyclohexane, Triton X-100, and 6.03 g of n-hexanol, and stir thoroughly to form a microemulsion. Add the semi-finished catalyst B to the prepared microemulsion and impregnate for 4 hours. Then wash with deionized water until neutral, dry at 90°C for 4 hours, and calcine at 600°C for 2 hours. Obtain the semi-finished catalyst C.

[0093] (4) Weigh a certain amount of palladium nitrate and dissolve it in water. Add a certain amount of cyclohexane, Triton X-100, and 6.03 g of n-hexanol and stir thoroughly to form a microemulsion. Add the semi-finished catalyst C to the prepared microemulsion and impregnate for 4 hours. Wash with deionized water until neutral, dry at 90°C for 4 hours, and calcine at 600°C for 2 hours. The finished catalyst is obtained.

[0094] The particle size of the microemulsion prepared during the catalyst preparation process and the content of each component in the catalyst are shown in Table 4.

[0095] Before use, place it in a fixed-bed reactor and reduce it for 12 hours at 160°C using a mixed gas with a molar ratio of N2:H2 = 1:1.

[0096] Example 4

[0097] The catalyst composition and preparation steps are the same as in Example 3, and the evaluation of the raw material composition is shown in Table 5.

[0098] Example 5

[0099] The catalyst composition and preparation steps are the same as in Example 3, and the evaluation of the raw material composition is shown in Table 5.

[0100] Example 6

[0101] The catalyst composition and preparation steps are the same as in Example 3, and the evaluation of the raw material composition is shown in Table 5.

[0102] Example 7

[0103] Carrier: A commercially available bimodal spherical alumina carrier with a diameter of 4 mm was used. After high-temperature calcination for 4 hours, 100 g of the carrier was weighed, and its physical properties are shown in Table 3.

[0104] Catalyst preparation:

[0105] (1) Weigh out a certain amount of nickel nitrate and copper chloride, dissolve them in water, add a certain amount of cyclohexane, Triton X-100, and 6.03 g of n-hexanol, and stir thoroughly to form a microemulsion. Add the support to the prepared microemulsion and impregnate for 4 hours, then wash with deionized water until neutral, dry at 90°C for 4 hours, and calcine at 600°C for 2 hours. Semi-finished catalyst A is obtained.

[0106] (2) Weigh a certain amount of palladium nitrate salt and dissolve it in water, adjust the pH to 2, add the semi-finished catalyst A into the salt solution of Pd, impregnate and adsorb for 1 hour, dry at 110℃ for 2 hours, and calcine at 380℃ for 6 hours to obtain the semi-finished catalyst B.

[0107] (3) Weigh a certain amount of ferric chloride and dissolve it in deionized water. Immerse the semi-finished catalyst B in the prepared solution, dry it at 110°C for 3 hours, and calcine it at 500°C for 4 hours to obtain the semi-finished catalyst C.

[0108] (4) Weigh a certain amount of palladium nitrate and dissolve it in water. Add a certain amount of cyclohexane, Triton X-100, and 6.03 g of n-hexanol and stir thoroughly to form a microemulsion. Add the semi-finished catalyst C to the prepared microemulsion and impregnate for 4 hours. Wash with deionized water until neutral, dry at 90°C for 4 hours, and calcine at 600°C for 2 hours. The finished catalyst is obtained.

[0109] The particle size of the microemulsion prepared during the catalyst preparation process and the content of each component in the catalyst are shown in Table 4.

[0110] Before use, place it in a fixed-bed reactor and reduce it for 12 hours at 170°C using a mixed gas with a molar ratio of N2:H2 = 1:1.

[0111] Example 8

[0112] Carrier: A commercially available bimodal spherical alumina carrier with a diameter of 4 mm was used. After high-temperature calcination for 4 hours, 100 g of the carrier was weighed, and its physical properties are shown in Table 3.

[0113] Catalyst preparation:

[0114] (1) Weigh out a certain amount of nickel nitrate and copper chloride, dissolve them in water, add a certain amount of cyclohexane, Triton X-100, and 6.03 g of n-hexanol, and stir thoroughly to form a microemulsion. Add the support to the prepared microemulsion and impregnate for 4 hours, then wash with deionized water until neutral, dry at 90°C for 4 hours, and calcine at 600°C for 2 hours. Semi-finished catalyst A is obtained.

[0115] (2) Weigh a certain amount of palladium nitrate and dissolve it in water. Add a certain amount of cyclohexane, Triton X-100, and 6.03 g of n-hexanol and stir thoroughly to form a microemulsion. Add the semi-finished catalyst A to the prepared microemulsion and impregnate for 4 hours. Wash with deionized water until neutral, dry at 90°C for 4 hours, and calcine at 600°C for 2 hours. Obtain the semi-finished catalyst B.

[0116] (3) Weigh a certain amount of ferric chloride and dissolve it in deionized water. Immerse the semi-finished catalyst B in the prepared solution, dry it at 110°C for 3 hours, and calcine it at 500°C for 4 hours to obtain the semi-finished catalyst C.

[0117] (4) Weigh a certain amount of palladium nitrate salt and dissolve it in water, adjust the pH to 2, add the semi-finished catalyst C to the salt solution of Pd, impregnate and adsorb for 1 hour, dry at 110℃ for 2 hours, and calcine at 380℃ for 6 hours to obtain the finished catalyst.

[0118] The particle size of the microemulsion prepared during the catalyst preparation process and the content of each component in the catalyst are shown in Table 4.

[0119] Before use, place it in a fixed-bed reactor and reduce it for 12 hours at 150°C using a mixed gas with a molar ratio of N2:H2 = 1:1.

[0120] Comparative Example 1-1

[0121] Comparative Example 1-1 differs from Example 1 in that it does not have the microemulsion Pd loaded.

[0122] Carrier: A commercially available bimodal spherical alumina carrier with a diameter of 4 mm was used. 100 g of the carrier was calcined at high temperature for 4 hours. The calcination temperature and carrier properties are shown in Table 3.

[0123] Catalyst preparation:

[0124] (1) Weigh a certain amount of nickel nitrate and copper chloride and dissolve them in deionized water. Add a certain amount of cyclohexane, Triton X-100 and n-butanol and stir thoroughly to form a microemulsion. Impregnate 100g of the carrier into the prepared microemulsion. After impregnation for 1 hour, wash with deionized water until neutral. Dry at 120℃ for 2 hours and calcine at 550℃ for 5 hours to obtain the semi-finished catalyst A1.

[0125] (2) Weigh ferric chloride, prepare a solution with deionized water, immerse catalyst A1 in the above solution, shake, and after the solution is completely absorbed, dry at 110°C for 3 hours and calcine at 500°C for 4 hours to obtain semi-finished catalyst B1.

[0126] (3) Weigh a certain amount of palladium nitrate, dissolve it in deionized water, adjust the pH to 1, add the semi-finished catalyst B1 to the solution, impregnate and adsorb for 1 hour, dry at 110℃ for 2 hours, and calcine at 380℃ for 6 hours to obtain the finished catalyst.

[0127] The particle size of the microemulsion prepared during the catalyst preparation process and the content of each component in the catalyst are shown in Table 4.

[0128] Before use, place it in a fixed-bed reactor and reduce it for 12 hours at 190°C using a mixed gas with a molar ratio of N2:H2 = 1:1.

[0129] Comparative Examples 1-2

[0130] The difference between Comparative Examples 1 and 2 and Example 1 is that there was no microemulsion Pd loading, and the catalyst reduction temperature was 450°C.

[0131] Carrier: A commercially available bimodal spherical alumina carrier with a diameter of 4 mm was used. 100 g of the carrier was calcined at high temperature for 4 hours. The calcination temperature and carrier properties are shown in Table 3.

[0132] Catalyst preparation:

[0133] (1) Weigh a certain amount of nickel nitrate and copper chloride and dissolve them in deionized water. Add a certain amount of cyclohexane, Triton X-100 and n-butanol and stir thoroughly to form a microemulsion. Impregnate 100g of the carrier into the prepared microemulsion. After impregnation for 1 hour, wash with deionized water until neutral. Dry at 120℃ for 2 hours and calcine at 550℃ for 5 hours to obtain the semi-finished catalyst A1.

[0134] (2) Weigh ferric chloride, prepare a solution with deionized water, immerse catalyst A1 in the above solution, shake, and after the solution is completely absorbed, dry at 110°C for 3 hours and calcine at 500°C for 4 hours to obtain semi-finished catalyst B1.

[0135] (3) Weigh a certain amount of palladium nitrate, dissolve it in deionized water, adjust the pH to 1, add the semi-finished catalyst B1 to the solution, impregnate and adsorb for 1 hour, dry at 110℃ for 2 hours, and calcine at 380℃ for 6 hours to obtain the finished catalyst.

[0136] The particle size of the microemulsion prepared during the catalyst preparation process and the content of each component in the catalyst are shown in Table 4.

[0137] Before use, place it in a fixed-bed reactor and reduce it for 12 hours at 450°C using a mixed gas with a molar ratio of N2:H2 = 1:1.

[0138] Comparative Examples 1-3

[0139] The difference between Comparative Examples 1-3 and Example 1 is that the solution-loaded Pd is replaced with Ag.

[0140] Carrier: A commercially available bimodal spherical alumina carrier with a diameter of 4 mm was used. 100 g of the carrier was calcined at high temperature for 4 hours. The calcination temperature and carrier properties are shown in Table 3.

[0141] Catalyst preparation:

[0142] (1) Weigh a certain amount of nickel nitrate and copper chloride and dissolve them in deionized water. Add a certain amount of cyclohexane, Triton X-100 and n-butanol and stir thoroughly to form a microemulsion. Impregnate 100g of the carrier into the prepared microemulsion. After impregnation for 1 hour, wash with deionized water until neutral. Dry at 120℃ for 2 hours and calcine at 550℃ for 5 hours to obtain the semi-finished catalyst A1.

[0143] (2) Weigh ferric chloride and prepare a solution with deionized water. Add the semi-finished catalyst A1 to the solution, shake, and after the solution is completely absorbed, dry at 110°C for 3 hours and calcine at 500°C for 4 hours to obtain the semi-finished catalyst B1.

[0144] (3) Weigh a certain amount of silver nitrate, dissolve it in deionized water, adjust the pH to 1, then immerse the semi-finished catalyst B1 in the prepared Ag salt solution, immerse and adsorb for 1 hour, dry at 110℃ for 2 hours, and calcine at 380℃ for 6 hours to obtain the finished catalyst.

[0145] The particle size of the microemulsion prepared during the catalyst preparation process and the content of each component in the catalyst are shown in Table 4.

[0146] Before use, place it in a fixed-bed reactor and reduce it for 12 hours at 190°C using a mixed gas with a molar ratio of N2:H2 = 1:1.

[0147] Comparative Example 2

[0148] In Comparative Example 2, there is no load of Pd.

[0149] Carrier: A commercially available bimodal spherical carrier with a diameter of 4 mm was used, consisting of 90 wt% alumina and 10 wt% titanium oxide. After high-temperature calcination for 4 hours, 100 g of the carrier was weighed, and its physical properties are shown in Table 3.

[0150] Catalyst preparation:

[0151] (1) Weigh out a certain amount of nickel nitrate and copper nitrate, dissolve them in deionized water, add a certain amount of cyclohexane, 14.3g Triton X-100, and 13.60g n-hexanol, and stir thoroughly to form a microemulsion. Add the support to the prepared microemulsion and impregnate for 1 hour, then wash with deionized water until neutral, dry at 120℃ for 2 hours, and calcine at 550℃ for 5 hours. Obtain the semi-finished catalyst A1.

[0152] (2) Weigh a certain amount of ferric nitrate and dissolve it in water. Add the semi-finished catalyst A1 to the Fe salt solution, impregnate and adsorb for 1 hour, dry at 110°C for 2 hours, and calcine at 380°C for 6 hours to obtain the finished catalyst.

[0153] The particle size of the microemulsion prepared during the catalyst preparation process and the content of each component in the catalyst are shown in Table 4.

[0154] Before use, place it in a fixed-bed reactor and reduce it for 12 hours at 180°C using a mixed gas with a molar ratio of N2:H2 = 1:1.

[0155] Comparative Example 3

[0156] In Comparative Example 3, there was no Fe loading in the solution, but the Pd content in the solution was relatively high.

[0157] Carrier: A commercially available bimodal spherical carrier with a diameter of 4 mm was used, consisting of 90 wt% alumina and 10 wt% titanium oxide. After high-temperature calcination for 4 hours, 100 g of the carrier was weighed, and its physical properties are shown in Table 3.

[0158] Catalyst preparation:

[0159] (1) Weigh out a certain amount of nickel nitrate and copper nitrate, dissolve them in deionized water, add a certain amount of cyclohexane, 14.3g Triton X-100, and 13.60g n-hexanol, and stir thoroughly to form a microemulsion. Add the support to the prepared microemulsion and impregnate for 1 hour, then wash with deionized water until neutral, dry at 120℃ for 2 hours, and calcine at 550℃ for 5 hours. Obtain the semi-finished catalyst A1.

[0160] (2) Weigh a certain amount of palladium nitrate, dissolve it in deionized water, adjust the pH to 1, and then immerse the semi-finished catalyst A1 in the prepared palladium salt solution. After immersion and adsorption for 1 hour, dry it at 110°C for 2 hours and calcine it at 380°C for 6 hours to obtain the semi-finished catalyst B1.

[0161] (3) Weigh a certain amount of palladium nitrate and dissolve it in water. Add a certain amount of cyclohexane, Triton X-100, and 6.03 g of n-hexanol and stir thoroughly to form a microemulsion. Add the semi-finished catalyst B1 to the prepared microemulsion and impregnate for 4 hours. Wash with deionized water until neutral, dry at 90°C for 4 hours, and calcine at 600°C for 2 hours. The finished catalyst is obtained.

[0162] The particle size of the microemulsion prepared during the catalyst preparation process and the content of each component in the catalyst are shown in Table 4.

[0163] Before use, place it in a fixed-bed reactor and reduce it for 12 hours at 180°C using a mixed gas with a molar ratio of N2:H2 = 1:1.

[0164] Comparative Example 4

[0165] In Comparative Example 4, there was no loading of microemulsion Ni, Cu, or Pd.

[0166] Carrier: A commercially available spherical alumina carrier with a single-peak pore distribution and a diameter of 4 mm was used. After high-temperature calcination for 4 hours, 100 g of the carrier was weighed, and its physical properties are shown in Table 3.

[0167] Catalyst preparation:

[0168] (1) Weigh a certain amount of ferric chloride and dissolve it in deionized water. Immerse the carrier in the prepared solution. After the solution is completely absorbed, dry at 100°C for 4 hours and calcine at 400°C for 6 hours to obtain the required catalyst semi-finished product, catalyst A1.

[0169] (2) Weigh a certain amount of palladium chloride salt and dissolve it in water to adjust the pH to 3. Add the weighed support of the semi-finished catalyst A1 to the salt solution of Pd, impregnate and adsorb for 2 hours, dry at 120℃ for 1 hour, and calcine at 450℃ for 4 hours to obtain the finished catalyst.

[0170] The contents of each component in the catalyst are shown in Table 4.

[0171] Before use, place it in a fixed-bed reactor and reduce it for 12 hours at 350°C using a mixed gas with a molar ratio of N2:H2 = 1:1.

[0172] Comparative Example 5

[0173] In Comparative Example 5, Ni and Cu in the microemulsion were replaced by Ni and Zn.

[0174] Carrier: A commercially available bimodal spherical alumina carrier with a diameter of 4 mm was used. After high-temperature calcination for 4 hours, 100 g of the carrier was weighed, and its physical properties are shown in Table 3.

[0175] Catalyst preparation:

[0176] (1) Weigh a certain amount of ferric chloride and dissolve it in deionized water. Add the carrier to the prepared solution, dry at 110°C for 3 hours, and calcine at 500°C for 4 hours to obtain the semi-finished catalyst A1.

[0177] (2) Weigh a certain amount of palladium nitrate salt and dissolve it in water, adjust the pH to 2, add the semi-finished catalyst A1 to the salt solution of Pd, impregnate and adsorb for 1 hour, dry at 110℃ for 2 hours, and calcine at 380℃ for 6 hours to obtain the semi-finished catalyst B1.

[0178] (3) Weigh out a certain amount of nickel nitrate and zinc nitrate, dissolve them in water, add a certain amount of cyclohexane, Triton X-100, and 6.03 g of n-hexanol, and stir thoroughly to form a microemulsion. Add the semi-finished catalyst B1 to the prepared microemulsion and impregnate for 4 hours. Then wash with deionized water until neutral, dry at 90°C for 4 hours, and calcine at 600°C for 2 hours to obtain the semi-finished catalyst C1.

[0179] (4) Weigh a certain amount of palladium nitrate and dissolve it in water. Add a certain amount of cyclohexane, Triton X-100, and 6.03 g of n-hexanol and stir thoroughly to form a microemulsion. Add the semi-finished catalyst C1 to the prepared microemulsion and impregnate for 4 hours. Wash with deionized water until neutral, dry at 90°C for 4 hours, and calcine at 600°C for 2 hours. The finished catalyst is obtained.

[0180] The particle size of the microemulsion prepared during the catalyst preparation process and the content of each component in the catalyst are shown in Table 4.

[0181] Before use, place it in a fixed-bed reactor and reduce it for 12 hours at 160°C using a mixed gas with a molar ratio of N2:H2 = 1:1.

[0182] Table 3 Catalyst Support Properties

[0183]

[0184] Table 4 Content of active components in catalyst

[0185]

[0186] The performance of the above catalyst was evaluated in a fixed-bed reactor. The composition of the reactants is shown in Table 5, and the evaluation results are shown in Table 6.

[0187] Table 5 Evaluation of Material Composition

[0188]

[0189]

[0190] Table 6 Evaluation Results

[0191]

[0192]

[0193] 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 selective hydrogenation method for ethane cracking to olefins, comprising selectively hydrogenating ethylene feedstock exiting from the top of a de-ethaner column to remove acetylene, wherein the reaction conditions are: reactor inlet temperature 50℃~95℃, reaction pressure 1.5~3.0MPa, and space velocity 8000~14000h⁻¹. -1 The catalyst support is alumina or mainly alumina, with a bimodal pore structure, and the specific surface area of ​​the catalyst is 3–10 m². 2 / g, wherein the pore size of the micropores is 56-75nm and the pore size of the macropores is 300-680nm; the catalyst contains at least Pd, Fe, Ni, and Cu, wherein Pd is supported in both microemulsion and solution methods, Ni and Cu are supported in microemulsion, and Fe is supported in solution; based on 100% of the catalyst mass, the Pd content is 0.008-0.015%, the Fe content is 0.7-2.3%, the Ni content is 0.5-8.0%, the weight ratio of Cu to Ni is 0.1-0.9, and the Pd content in the microemulsion-supported catalyst is 1 / 15 to 1 / 4 of the Pd content in the solution-supported catalyst; wherein, Ni, Cu, and Pd loaded in the microemulsion are mainly distributed in the macropores of the support in the range of 300–680 nm.

2. The selective hydrogenation method for ethane cracking to olefins according to claim 1, characterized in that, The reaction conditions were: reactor inlet temperature 60℃~90℃, reaction pressure 2.0~2.8MPa, and space velocity 9000~12000h⁻¹. -1 Based on the mass of the catalyst (100%), the Fe content is 0.8~2.0%, the Ni content is 2.0~5.8%, the weight ratio of Cu to Ni is 0.3~0.8, and the Pd content of the microemulsion-loaded catalyst is 1 / 10 to 1 / 5 of the Pd content of the solution-loaded catalyst.

3. The selective hydrogenation method for ethane cracking to olefins according to claim 1, characterized in that, After the cracked gas is washed with alkali and dehydrated, the composition of the feedstock to be hydrogenated at the top of the de-ethaner tower is mainly as follows by volume ratio: H2 25-45%, CO 0.02-0.2%, methane 10-30%, acetylene 0.15-0.3%, and ethylene 30-45%.

4. The selective hydrogenation method for ethane cracking to olefins according to claim 1, characterized in that... The reactor is a fixed-bed reactor, which consists of two or three adiabatic beds connected in series.

5. The selective hydrogenation method for ethane cracking to olefins according to claim 1, characterized in that... The catalyst support is alumina or mainly alumina, and the Al2O3 crystal form is α, θ or a mixture thereof; the alumina content in the catalyst support is above 80 wt%, and the support also contains magnesium oxide and titanium oxide.

6. The selective hydrogenation method for ethane cracking to olefins according to claim 1, characterized in that... The catalyst reduction temperature is 150–200℃.

7. The selective hydrogenation method for ethane cracking to olefins according to claim 1, characterized in that... During catalyst preparation, the order of Pd solution loading and Ni / Cu loading is not limited. The Pd microemulsion loading step is after the Ni and Cu microemulsion loading steps. The order of Fe solution loading and Pd solution loading is not limited.

8. The selective hydrogenation method for ethane cracking to olefins according to claim 1 or 7, characterized in that... The microemulsion loading process includes: dissolving the precursor salt in water, adding an oil phase, a surfactant, and a co-surfactant, and stirring thoroughly to form a microemulsion, wherein the oil phase is an alkane or cycloalkanes, the surfactant is an ionic surfactant and / or a nonionic surfactant, and the co-surfactant is an organic alcohol.

9. The selective hydrogenation method for ethane cracking to olefins according to claim 1, characterized in that... The preparation process specifically includes the following steps: (1) Dissolve the precursor salts of Ni and Cu in water, add oil phase, surfactant and co-surfactant, stir thoroughly to form microemulsion, control the microemulsion particle size to be greater than 75nm and less than 680nm, the weight ratio of surfactant and co-surfactant is 1.0 to 1.2, the weight ratio of water phase to oil phase is 4.5 to 5.8, and the weight ratio of surfactant to oil phase is 0.1 to 0.35; add the support to the prepared microemulsion and impregnate for 0.5 to 4 hours, filter out the residual liquid, dry at 60 to 120℃ for 1 to 6 hours, and calcine at 300 to 600℃ for 2 to 8 hours to obtain semi-finished catalyst A; (2) The loading of Fe was carried out by saturation impregnation. The Fe salt solution was prepared with a saturation water absorption rate of 80-110% of the support. The pH was adjusted to 1-5. After loading Fe, the semi-finished catalyst A was calcined at 500-550℃ for 4-6 hours to obtain the semi-finished catalyst B. (3) Dissolve the precursor salt of Pd in ​​water, adjust the pH to 1.5-2.5, add the semi-finished catalyst B to the salt solution of Pd, impregnate and adsorb for 0.5-4h, dry at 100-120℃ for 1-4h, and calcine at 400-550℃ for 2-6h to obtain the semi-finished catalyst C. (4) Dissolve the Pd precursor salt in water, add the oil phase, surfactant and co-surfactant, stir thoroughly to form a microemulsion, control the microemulsion particle size to be greater than 75nm and less than 680nm, add the semi-finished catalyst C into the prepared microemulsion and impregnate for 0.5 to 4 hours, filter out the residual liquid, dry at 60 to 120℃ for 1 to 6 hours, and calcine at 300 to 600℃ for 2 to 8 hours to obtain the desired catalyst.

10. The selective hydrogenation method for ethane cracking to olefins according to claim 8, characterized in that... The oil phase is composed of C6-C8 saturated alkanes or cycloalkanes; the surfactant is an ionic surfactant and / or a nonionic surfactant; the co-surfactant is a C4-C6 alcohol.

11. The selective hydrogenation method for ethane cracking to olefins according to claim 8, characterized in that, The oil phase is cyclohexane or n-hexane, the surfactant is polyethylene glycol octylphenyl ether or hexadecyltrimethylammonium bromide, and the co-surfactant is n-butanol and / or n-pentanol.

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