Selective hydrogenation catalyst for C1~C3 fractions and its preparation and application

Abstract

The present invention discloses a selective hydrogenation catalyst for C1-C3 fractions, wherein the carrier of the catalyst has a bimodal pore distribution structure, and the catalyst contains at least Pd, Ni and Fe; wherein Pd is loaded by a microemulsion method and a solution method; Ni is loaded by a microemulsion method; and Fe is loaded by a solution method; based on the mass of the carrier as 100%, the total Pd content loaded by the microemulsion method and the solution method is 0.009-0.0245%, wherein the Pd content loaded by the solution method is 0.007-0.015%, and the ratio of Pd loaded by the solution method to Fe loaded by the solution method is 0.004-0.024:1; the Ni content is 1.0-2.5%; and the Fe content is 0.5-1.5%. The present invention also discloses its preparation and application. The catalyst of the present invention has a significantly lower content of precious metal Pd than traditional catalysts, effectively reducing the catalyst cost.

Description

Technical Field

[0001] The present invention relates to a selective hydrogenation catalyst for C1-C3 fractions and its preparation and application. Background Art

[0002] Ethylene, obtained by steam cracking petroleum hydrocarbons (such as ethane, naphtha, diesel, and hydroprocessing tail oil), contains 0.2% to 2.5% acetylene by mass. During polymerization, the acetylene in ethylene reduces the activity of the polymerization catalyst and affects the physical properties of the polymer, so it must be removed. Currently, selective hydrogenation is widely used in industry to remove acetylene, primarily using precious metal catalysts such as Pd, Pt, and Au. To ensure that the ethylene produced by acetylene hydrogenation and the ethylene already in the feedstock do not continue to hydrogenate to ethane, resulting in ethylene loss, a high catalyst selectivity is essential for optimal economic performance.

[0003] Based on the relative position of the C2 hydrogenation reactor and the demethanizer, C2 hydrogenation is divided into pre-hydrogenation and post-hydrogenation. The C2 pre-hydrogenation reactor is located before the demethanizer, and the hydrogenated feed generally contains C1, C2, and C3 fractions. The C1 fraction contains not only hydrogen and methane, but also CO. The general composition of the pre-depropanization hydrogenation feed is: H2 15%-30%, C2H6 4%-10%, C2H4 25%-40%, C2H2 0.4%-0.7%, C3H6 8%-11%, C3H8 1%-2%, propyne 0.1%-0.6%, propadiene 0.1%-0.6%, and CO 0.04%-0.15%.

[0004] Precious metal catalysts are highly active, but they are prone to generating green oil during use, which can cause the catalyst to coke and deactivate, affecting its stability and service life. CN200810119385.8 discloses a non-precious metal supported selective hydrogenation catalyst comprising a support, a primary active component and a secondary active component supported on the support, wherein the primary active component is Ni and the secondary active component is selected from at least one of Mo, La, Ag, Bi, Cu, Nd, Cs, Ce, Zn, and Zr. Both the primary active component and the secondary active component are amorphous and have an average particle size of less than 10 nm. The catalyst is prepared by a microemulsion method, and its support is a non-oxidizing porous material.

[0005] Catalysts for the selective hydrogenation of alkynes and dienes are prepared by loading a noble metal, such as palladium, onto a porous inorganic material carrier (US4762956). To increase catalyst selectivity and reduce catalyst deactivation caused by the green oil produced by oligomerization during hydrogenation, existing technologies employ methods that incorporate Group IB elements as co-catalysts, such as Pd-Au (US4490481), Pd-Ag (US4404124), and Pd-Cu (US3912789), or alkali or alkaline earth metals (US5488024). The carriers used include alumina, silica (US5856262), and honeycomb philadelphite (CN1176291). US4404124 describes a selective hydrogenation catalyst with a palladium shell distribution as the active component, prepared by a stepwise impregnation process. The catalyst is applicable to the selective hydrogenation of C2 and C3 fractions to eliminate acetylene from ethylene and propyne and propadiene from propylene. US5587348 uses alumina as a carrier, modulates the interaction between silver and palladium as co-catalysts, and adds alkali metals and chemically bonded fluorine to produce a high-performance carbon dihydrogenation catalyst. This catalyst reduces green oil production, improves ethylene selectivity, and reduces oxygenate production. US5519566 discloses a wet reduction method for preparing a silver and palladium catalyst. By adding an organic or inorganic reducing agent to the impregnation solution, a silver and palladium two-component selective hydrogenation catalyst is prepared.

[0006] The above traditional carbon dihydrogenation catalysts are all prepared by impregnation method, and their active phase is Pd and Ag bimetallic. This method has the following disadvantages: (1) Affected by the pore structure of the carrier, the dispersion of the active components cannot be precisely controlled and is highly random. (2) Affected by the surface tension and solvation effect of the impregnation liquid, the metal active component precursors are deposited on the carrier surface in the form of aggregates and cannot form a uniform distribution. (3) Carbon dihydrogenation requires high catalyst selectivity. The traditional preparation method promotes the role of its auxiliary agent by increasing the amount of Ag, which leads to the obstruction of hydrogen transfer, the increase in the possibility of polymerization reaction, the increase in the amount of green oil generated, and the impact on the life of the catalyst. The occurrence of the above three phenomena can easily lead to poor dispersion of the metal active components, low reaction selectivity, and high green oil generation, which in turn affects the overall performance of the catalyst.

[0007] ZL201110086174.0 forms a polymer coating of a certain thickness on the carrier surface by adsorbing a specific polymer compound onto the carrier. Compounds with functional groups react with the polymer to impart functional groups capable of complexing with the active components. The active components then undergo complexation reactions on the functional groups on the carrier surface, ensuring the orderly and highly dispersed active components. Using this patented method, the carrier adsorbs the specific polymer compound, which chemically adsorbs the polymer via the hydroxyl groups of alumina. The amount of polymer adsorbed by the carrier is limited by the number of hydroxyl groups on the alumina. The complexation between the functionalized polymer and Pd is weak, sometimes failing to meet the required active component loading, and some active components may remain in the impregnation solution, increasing catalyst costs.

[0008] To improve the catalyst's anti-coking performance and reduce the degree of surface coking, recent publications have disclosed C2 selective hydrogenation catalysts and preparation methods that utilize a bimodal pore support and a microemulsion method to support the active component. Patent ZL201310114077.7 discloses a selective hydrogenation catalyst whose support is primarily alumina with a bimodal pore distribution, with small pores within 50 nm and large pores between 60 and 800 nm. Based on 100% catalyst mass, the catalyst contains 0.01 to 0.5% Pd by weight, distributed in a shell with a thickness of 1 to 500 μm, and 0.2 to 5% Ni by weight. The Ni, the anti-coking component, is prepared by microemulsion, with the microemulsion particle size controlled to be larger than the carrier's small pores, so that the Ni is primarily distributed in the carrier's large pores. Patent ZL201310114079.6 discloses a preparation method for a hydrogenation catalyst whose support is primarily alumina with a bimodal pore distribution. The catalyst contains dual 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. The active component, Pd, is primarily distributed on the support surface, particularly in the small pores. Patent ZL201310114371.8 discloses a method for the selective hydrogenation of C2 fractions suitable for pre-depropanization and pre-hydrogenation processes. This method utilizes a selective hydrogenation catalyst whose support is, or primarily, alumina and has a bimodal pore distribution. It contains dual active components, Pd and Ni, with the anti-coking component, Ni, primarily distributed in the macropores. This method improves the catalyst's anti-coking performance, but the reduction temperature for the single Ni component in the macropores of the catalyst support reaches above 500°C. At this temperature, the reduction causes the active component, Pd, to aggregate, significantly reducing catalyst activity. To compensate for this loss in catalyst activity, the dosage of the active component must be increased, resulting in decreased catalyst selectivity and reduced active component utilization.

[0009] Patent application ZL201910992442.1 discloses a catalyst with a dual pore size distribution: Ni-Cu and Pd are distributed in the macropores, loaded in two steps using a microemulsion method, and Pd is loaded in the small pores using a solution method. The selective hydrogenation of acetylene occurs primarily in the small pores, with the byproducts generated in the reaction undergoing saturated hydrogenation at the Ni-Cu active centers in the macropores, significantly reducing the catalyst's coking rate. However, the catalyst contains a high content of Pd, the primary active component, resulting in high catalyst cost. Summary of the Invention

[0010] The present invention aims to improve the selectivity of hydrogenation of C1-C3 fractions at a lower cost.

[0011] As one aspect of the present invention, it relates to a selective hydrogenation catalyst for C1-C3 fractions, wherein the carrier of the catalyst has a bimodal pore distribution structure, and the catalyst contains at least Pd, Ni and Fe; wherein the Pd is loaded by a microemulsion method and a solution method; the Ni is loaded by a microemulsion method; and the Fe is loaded by a solution method; based on the mass of the carrier as 100%, the total content of Pd loaded by the microemulsion method and the solution method is 0.009-0.0245%, wherein the content of Pd loaded by the solution method is 0.007-0.015%, and the ratio of Pd loaded by the solution method to Fe loaded by the solution method is 0.004-0.024:1; the content of Ni is 1.0-2.5%; and the content of Fe is 0.5-1.5%.

[0012] In a specific embodiment, the bimodal pore distribution structure has a small pore diameter of 30 to 80 nm and a large pore diameter of 130 to 800 nm. In a specific embodiment, the specific surface area of ​​the catalyst is 3 to 15 m 2 / g.

[0013] Another aspect of the present invention relates to a method for preparing the aforementioned selective hydrogenation catalyst for C1-C3 fractions. In the method, nickel and iron are first loaded, followed by palladium. In a specific embodiment, nickel is loaded using a microemulsion method, iron is loaded using a solution method, and palladium is loaded using a microemulsion method and / or a solution method.

[0014] In a specific embodiment, the method includes:

[0015] (1) adding the carrier to a Ni microemulsion for impregnation, calcining, and then adding an aqueous solution of an Fe precursor salt for impregnation and calcining; or, adding the carrier to an aqueous solution of an Fe precursor salt, calcining, and then adding the carrier to a Ni microemulsion for impregnation and calcining; the Ni microemulsion is formed by adding an oil phase, a surfactant, and a cosurfactant to the aqueous solution of the Ni precursor salt and stirring, and the particle size of the microemulsion is greater than 80 nm and less than 800 nm;

[0016] (2) adding the product prepared in step (1) to an aqueous solution of a Pd precursor salt, aging, drying, and roasting, and then adding a Pd microemulsion for impregnation and roasting; or, adding the product prepared in step (1) to a Pd microemulsion for impregnation and roasting, and then adding it to an aqueous solution of a Pd precursor salt for aging, drying, and roasting; the Pd microemulsion is formed by adding an oil phase, a surfactant, and a cosurfactant to the aqueous solution of the Pd precursor salt and stirring, and the particle size of the microemulsion is greater than 80 nm and less than 800 nm.

[0017] In steps (1) and (2), the mass ratio of water in the aqueous solution to the oil phase is 2.5 to 4.5:1; the mass ratio of the surfactant to the oil phase is 0.1 to 0.4:1; and the mass ratio of the surfactant to the co-surfactant is 1.0 to 1.40:1.

[0018] The oil phase in step (1) is an alkane, the surfactant is Triton X-100 or CTAB, and the cosurfactant is an alcohol. Further, the oil phase in step (1) is cyclohexane or n-hexane, and the cosurfactant is n-butanol, n-pentanol, or n-octanol.

[0019] The oil phase in step (2) is an alkane, the surfactant is Triton X-100 or CTAB, and the cosurfactant is an alcohol. Furthermore, the oil phase in step (2) is cyclohexane or n-hexane, and the cosurfactant is n-butanol, n-pentanol, or n-octanol.

[0020] For the convenience of implementation, the Fe, Ni and Pd precursor salts should all be soluble salts.

[0021] The calcination temperature in step (1) is 400-600°C.

[0022] The calcination temperature in step (2) is 250-600°C.

[0023] The inventors found that in the catalyst of the present invention, two active centers are formed, one of which is the alkyne selective hydrogenation active center formed by Fe / Pd; the other is the byproduct hydrogenation active center formed by Ni / Pd, which is beneficial to improving the activity and selectivity of the catalyst. In order to reduce the cost of the catalytic reaction, the inventors considered using low-valent metals to replace the precious metals in the catalyst, but found that after using the low-valent metal Fe to replace the precious metal, the catalytic activity was significantly reduced, and the catalytic reaction needed to be carried out at a higher temperature, resulting in ethylene being easily polymerized at high temperatures. Finally, the inventors found that after loading iron, a small amount of palladium was loaded, which greatly improved the activity of the iron active center. Compared with traditional catalysts, it not only reduced the cost of the catalyst, but also did not cause a significant decrease in its activity. . It is speculated that the reason may be that palladium has a high hydrogen adsorption effect, which can realize the transfer of hydrogen from palladium atoms to the iron active center, thereby improving the activity of the iron active center.

[0024] Another aspect of the present invention relates to a C2 hydrogenation process using the aforementioned C1-C3 fraction selective hydrogenation catalyst. The reduction temperature of the catalyst of the present invention is preferably 180-220°C.

[0025] The catalyst of this invention can reduce the precious metal Pd content by up to 70% compared to conventional catalysts, significantly reducing catalyst costs. Because the non-precious metal Fe has weaker CO adsorption than the precious metal Pd, the catalyst of this invention is less sensitive to CO fluctuations and can adapt to operating conditions with significantly fluctuating CO levels.

[0026] The catalyst operation cycle of the present invention is significantly extended. At the beginning of the hydrogenation reaction, the selective hydrogenation reaction of acetylene mainly occurs in the small pores. As the catalyst operation time increases, some by-products with larger molecular weights are generated on the catalyst surface. Due to their larger molecular size, these substances enter the large pores more frequently and stay there for a longer time. Under the action of the nickel catalyst, double bonds are hydrogenated to produce saturated hydrocarbons or aromatic hydrocarbons without isolated double bonds, and no substances with larger molecular weights are produced.

[0027] The catalyst of the present invention effectively reduces catalyst costs. Conventional catalysts use Pd as the primary active component for selective hydrogenation, with its content typically around 0.03%. Precious metals account for over 60% of the catalyst cost. However, in the present invention, the precious metal is replaced with Fe, a non-precious metal. Pd becomes the co-active component for selective hydrogenation, with its content being up to half that of conventional catalysts. This significantly reduces catalyst costs.

[0028] The catalyst of the present invention improves its resistance to CO fluctuations. In conventional catalysts, the outer D orbital of Pd is completely empty, allowing CO's lone pair electrons to easily enter the empty Pd orbital. However, the outer P orbital of the Fe atom is half-filled, making it difficult for CO's lone pair electrons to enter the orbital. This makes the adsorption strength of CO on the Fe atom weaker than that of the precious metal Pd, thus reducing its sensitivity to CO fluctuations. This improved resistance to CO fluctuations allows it to adapt to operating conditions with large fluctuations in CO content. Compared with conventional catalysts, the catalyst of the present invention reduces catalyst cost, extends catalyst life, and improves its resistance to CO fluctuations. DETAILED DESCRIPTION

[0029] Hereinafter, the technical solution of using iron to partially replace palladium to prepare a selective hydrogenation catalyst according to the present invention will be described in detail through specific examples.

[0030] Source of raw materials or equipment:

[0031]

[0032] Sources of reagents and raw materials:

[0033]

[0034] Evaluation and analysis methods:

[0035] Analytical test methods:

[0036] Specific table: GB / T-5816;

[0037] Pore ​​volume: GB / T-5816;

[0038] Active component content in catalyst: atomic absorption method;

[0039] Particle size distribution of Ni / Cu alloy microemulsion: Dynamic light scattering particle size analyzer, analyzed on M286572 dynamic light scattering analyzer;

[0040] The conversion rate and selectivity in the embodiment are calculated according to the following formula:

[0041] Acetylene conversion rate (%) = 100 × △ acetylene / inlet acetylene content

[0042] Ethylene selectivity (%) = 100 × Δethylene / Δacetylene

[0043] Example 1

[0044] Support: Commercially available bimodal pore distribution spherical alumina support with a diameter of 4 mm, calcined at 1350 ° C, with a specific surface area of ​​3 m 2 / g, water absorption rate 35%, small pore diameter 55-80nm, large pore diameter 500-800nm, weighing 100g of the carrier. The calcination temperature and carrier physical properties are shown in Table 3.

[0045] Catalyst preparation:

[0046] (1) Weigh 3.11 g of nickel nitrate and dissolve it in 40 ml of deionized water. Add 8.88 g of cyclohexane, 0.89 g of Triton X-100, and 0.64 ml of n-butanol, and stir thoroughly to form a microemulsion. Then, soak 100 g of the carrier in the prepared microemulsion. After the emulsion is completely absorbed, dry it at 60°C and calcine it at 600°C for 5 h to obtain a semi-finished catalyst A.

[0047] (2) Weigh 4.36 g of ferric nitrate and dissolve it in 35 g of deionized water. Then add the semi-finished catalyst A to the Fe salt solution. After the solution is completely absorbed, age it for 4 hours, dry it at 120°C, and calcine it at 250°C for 6 hours to obtain the semi-finished catalyst B.

[0048] (3) 11.67 mg of palladium chloride was weighed and dissolved in 35 g of deionized water, and the pH was adjusted to 1.5. The semi-finished catalyst B was then added to the Pd salt solution, aged for 10 hours, dried at 120°C, and calcined at 500°C for 4 hours to obtain the semi-finished catalyst C;

[0049] (4) Weigh 3.33 mg of palladium chloride and dissolve it in 40 ml of deionized water. Add 8.88 g of cyclohexane, 0.89 g of Triton X-100, and 0.64 g of n-butanol, and stir thoroughly to form a microemulsion. Then, impregnate the semi-finished catalyst C into the prepared microemulsion. After the emulsion is completely absorbed, dry it at 60°C for 6 hours and calcine it at 550°C for 4 hours to obtain the desired catalyst.

[0050] The particle size of the microemulsion prepared in steps (1) and (4) was 800 nm as determined by dynamic light scattering.

[0051] The prepared catalyst was measured by atomic absorption spectrometry. Based on the support as 100%, in Example 1, the Pd content was 0.009%, the Ni content was 1%, and the Fe content was 1%. The Pd content in the solution method was 0.007%, and the Pd content in the emulsion method was 0.002%.

[0052] Before use, it was placed in a fixed bed reaction device and reduced with a mixed gas with a molar ratio of N2:H2=1:1 at a temperature of 220°C for 12 hours.

[0053] Comparative Example 1 provides a catalyst, the carrier of which is the same as that of Example 1, except that Ni is not loaded in Comparative Example 1.

[0054] Catalyst preparation:

[0055] (1) Weigh 4.36 g of ferric nitrate and dissolve it in 35 g of deionized water. Then add the semi-finished catalyst A to the Fe salt solution. After the solution is completely absorbed, age it for 4 hours, dry it at 120° C., and calcine it at 250° C. for 6 hours to obtain the semi-finished catalyst A1.

[0056] (2) 11.67 mg of palladium chloride was weighed and dissolved in 35 g of deionized water, and the pH was adjusted to 1.5. The semi-finished catalyst B was then added to the Pd salt solution, aged for 10 hours, dried at 120° C., and calcined at 500° C. for 4 hours to obtain the semi-finished catalyst B;

[0057] (3) 3.33 mg of palladium chloride was weighed and dissolved in 40 ml of deionized water. 8.88 g of cyclohexane, 0.89 g of Triton X-100, and 0.64 g of n-butanol were added and stirred thoroughly to form a microemulsion. The semi-finished catalyst C was impregnated into the prepared microemulsion. After the emulsion was completely absorbed, the catalyst was dried at 60°C for 6 hours and calcined at 550°C for 4 hours to obtain the desired catalyst.

[0058] The particle size of the microemulsion prepared in step (3) was determined to be 800 nm by dynamic light scattering.

[0059] The prepared catalyst was measured by atomic absorption spectrometry. Based on the support as 100%, the Pd content in Example 1 was 0.009% and the Fe content was 1%. The Pd content in the solution method was 0.007%, and the Pd content in the emulsion method was 0.002%.

[0060] Before use, it was placed in a fixed bed reaction device and reduced with a mixed gas with a molar ratio of N2:H2=1:1 at a temperature of 220°C for 12 hours.

[0061] Example 2 This example provides a catalyst, the carrier of which is a commercially available bimodal pore distribution spherical carrier with a diameter of 4 mm and a composition of 90% alumina and 10% titanium oxide. After calcination at 1310°C, the specific surface area is 10 m 2 / g, water absorption rate 45%, small pore diameter 45-65nm, large pore diameter 260-620nm, weigh 100g of the carrier.

[0062] Catalyst preparation:

[0063] (1) Weigh 2.33 g of ferric chloride and dissolve it in 45 g of deionized water. Add 100 g of the calcined carrier to the prepared Fe salt solution. After the solution is completely absorbed, age for 4 hours, dry at 100°C, and calcine at 500°C for 6 hours to obtain a semi-finished catalyst D.

[0064] (2) 3.54 g of nickel chloride was dissolved in 45 ml of deionized water, and 15.52 g of n-hexane, 4.66 g of CTAB, and 3.88 g of n-pentanol were added and stirred thoroughly to form a microemulsion. Semi-finished catalyst D was impregnated into the prepared microemulsion. After the emulsion was completely absorbed, the mixture was dried at 100° C. and calcined at 600° C. for 5 h to obtain semi-finished catalyst E.

[0065] (3) 17.32 mg of palladium nitrate was weighed and dissolved in 45 ml of deionized water. 15.52 g of n-hexane, 4.66 g of CTAB, and 3.88 g of n-pentanol were added and stirred thoroughly to form a microemulsion. Semi-finished catalyst E was impregnated into the prepared microemulsion. After the emulsion was completely absorbed, the mixture was dried at 100° C. and calcined at 500° C. for 4 hours to obtain semi-finished catalyst F.

[0066] (4) Weigh 21.65 mg of palladium nitrate and dissolve it in 45 g of deionized water. Adjust the pH to 1.6. Then add the semi-finished catalyst F to the palladium salt solution, age it for 10 hours, dry it at 120°C, and calcine it at 500°C for 4 hours to obtain the desired catalyst.

[0067] The particle size of the microemulsion prepared in steps (2) and (3) was 200 nm as determined by dynamic light scattering.

[0068] The prepared catalyst was measured by atomic absorption spectrometry. Based on the support as 100%, in Example 2, the Pd content was 0.018%, the Ni content was 1.6%, and the Fe content was 0.8%. The Pd content in the solution method was 0.01%, and the Pd content in the emulsion method was 0.008%.

[0069] Before use, it was placed in a fixed bed reaction device and reduced with a mixed gas with a molar ratio of N2:H2=1:1 at a temperature of 220°C for 12 hours.

[0070] Comparative Example 2 provides a catalyst having the same carrier as that used in Example 2 and the same catalyst preparation conditions as those in Example 2, except that Fe is not loaded in the solution method in Comparative Example 2.

[0071] Catalyst preparation:

[0072] (1) 3.54 g of nickel chloride was dissolved in 45 ml of deionized water, and 15.52 g of n-hexane, 4.66 g of CTAB, and 3.88 g of n-pentanol were added and stirred thoroughly to form a microemulsion. 100 g of the calcined support was immersed in the prepared microemulsion. After the emulsion was completely absorbed, the support was dried at 100° C. and calcined at 600° C. for 5 h to obtain the semi-finished catalyst D1.

[0073] (2) 17.32 mg of palladium nitrate was weighed and dissolved in 45 ml of deionized water. 15.52 g of n-hexane, 4.66 g of CTAB, and 3.88 g of n-pentanol were added and stirred thoroughly to form a microemulsion. The semi-finished catalyst F was impregnated into the prepared microemulsion. After the emulsion was completely absorbed, the mixture was dried at 100° C. and calcined at 500° C. for 4 hours to obtain the semi-finished catalyst E1.

[0074] (3) Weigh 21.65 mg of palladium nitrate and dissolve it in 45 g of deionized water. Adjust the pH to 1.6. Then, add the semi-finished catalyst E1 to the palladium salt solution, age it for 10 hours, dry it at 120°C, and calcine it at 500°C for 4 hours to obtain the desired catalyst.

[0075] The particle size of the microemulsion prepared in steps (1) and (2) was determined to be 200 nm by dynamic light scattering.

[0076] The prepared catalyst was measured by atomic absorption spectrometry. Based on the support as 100%, the Pd content in Example 2 was 0.018%, and the Ni content was 1.6%. The Pd content in the solution method was 0.01%, and the Pd content in the emulsion method was 0.008%.

[0077] Before use, it was placed in a fixed bed reaction device and reduced with a mixed gas with a molar ratio of N2:H2=1:1 at a temperature of 220°C for 12 hours.

[0078] Example 3

[0079] Carrier: A commercially available bimodal pore distribution spherical carrier with a diameter of 4 mm and a composition of 80% alumina and 20% magnesia was used. After calcination at 1250°C, the specific surface area was 15 m 2 / g, water absorption rate 51%, small pore diameter 30-55nm, large pore diameter 130-520nm, weigh 100g of the carrier.

[0080] Catalyst preparation:

[0081] (1) 7.78 g of nickel nitrate was weighed and dissolved in 51 ml of deionized water. 20.4 g of n-hexane, 8.16 g of CTAB, and 5.83 g of n-pentanol were added and stirred thoroughly to form a microemulsion. 100 g of the support was impregnated into the prepared microemulsion. After the emulsion was completely absorbed, the support was calcined at 400°C for 7 h to obtain the semi-finished catalyst H.

[0082] (2) Weigh 2.17 g of ferric nitrate and dissolve it in 51 g of deionized water. Then add the semi-finished catalyst H to the prepared Fe salt solution. After the solution is completely absorbed, age it for 6 hours, dry it at 120°C, and calcine it at 300°C for 6 hours to obtain the semi-finished catalyst J.

[0083] (3) Weigh 20 mg of palladium chloride and dissolve it in 51 g of deionized water, adjust the pH to 2.0, then add the semi-finished catalyst J to the Pd salt solution, age it for 10 hours, dry it at 120°C, and calcine it at 550°C for 4 hours to obtain the semi-finished catalyst K;

[0084] (4) Weigh 27.06 mg of palladium nitrate and dissolve it in 51 ml of deionized water. Add 20.4 g of n-hexane, 8.16 g of CTAB, and 5.83 g of n-pentanol, and stir thoroughly to form a microemulsion. Then, impregnate the semi-finished catalyst K into the prepared microemulsion. After immersion for 2 hours, wash it with deionized water until it is neutral, dry it at 60°C, and calcine it at 400°C for 6 hours to obtain the desired catalyst.

[0085] The particle size of the microemulsion prepared in steps (1) and (4) was determined to be 80 nm by dynamic light scattering.

[0086] The prepared catalyst was measured by atomic absorption spectrometry. Based on the support as 100%, in Example 3, the Pd content was 0.0245%, the Ni content was 2.5%, and the Fe content was 0.5%. The Pd content in the solution method was 0.012%, and the Pd content in the emulsion method was 0.0125%.

[0087] Before use, it was placed in a fixed bed reaction device and reduced with a mixed gas with a molar ratio of N2:H2=1:1 at a temperature of 180°C for 12 hours.

[0088] Comparative Example 3 provides a catalyst, wherein the carrier is the same as that of Example 3 and the preparation conditions are the same, except that, in Comparative Example 3, Pd is first loaded by the emulsion method.

[0089] Catalyst preparation:

[0090] (1) Weigh 27.06 mg of palladium nitrate and dissolve it in 51 ml of deionized water. Add 20.4 g of n-hexane, 8.16 g of CTAB, and 5.83 g of n-pentanol, and stir thoroughly to form a microemulsion. Then, 100 g of the calcined support was immersed in the prepared microemulsion. After the emulsion was completely absorbed, the support was dried at 60°C and calcined at 400°C for 6 hours to obtain a semi-finished catalyst H1.

[0091] (2) Weigh 2.17 g of ferric nitrate and dissolve it in 51 g of deionized water. Then add the semi-finished catalyst H1 to the prepared Fe salt solution. After the solution is completely absorbed, age it for 6 hours, dry it at 120°C, and calcine it at 300°C for 6 hours to obtain the semi-finished catalyst J1.

[0092] (3) Weigh 20 mg of palladium chloride and dissolve it in 51 g of deionized water, adjust the pH to 2.0, then add the semi-finished catalyst J1 to the Pd salt solution, age it for 10 hours, dry it at 120°C, and calcine it at 550°C for 4 hours to obtain the semi-finished catalyst K1;

[0093] (4) 7.78 g of nickel nitrate was dissolved in 51 ml of deionized water, and 20.4 g of n-hexane, 8.16 g of CTAB, and 5.83 g of n-pentanol were added and stirred thoroughly to form a microemulsion. 100 g of the support was immersed in the prepared microemulsion. After the emulsion was completely absorbed, the support was calcined at 400 °C for 7 h to obtain the desired catalyst.

[0094] The particle size of the microemulsion prepared in steps (1) and (4) was determined to be 80 nm by dynamic light scattering.

[0095] The prepared catalyst was measured by atomic absorption spectrometry. Based on the support as 100%, in Example 3, the Pd content was 0.0245%, the Ni content was 2.5%, and the Fe content was 0.5%. The Pd content in the solution method was 0.012%, and the Pd content in the emulsion method was 0.0125%.

[0096] Before use, it was placed in a fixed bed reaction device and reduced with a mixed gas with a molar ratio of N2:H2=1:1 at a temperature of 180°C for 12 hours.

[0097] Example 4

[0098] Support: A commercially available bimodal pore distribution spherical alumina support with a diameter of 3 mm was used. After calcination at 1330°C for 4 hours, the specific surface area was 7 m 2 / g, water absorption rate 48%, small pore diameter 50-70nm, large pore diameter 350-680nm, weigh 100g of the carrier.

[0099] Catalyst preparation:

[0100] (1) 4.67 g of nickel nitrate was dissolved in 40 ml of deionized water, and 10 g of cyclohexane, 1.6 g of Triton X-100, and 1.23 ml of n-butanol were added and stirred thoroughly to form a microemulsion. 100 g of the carrier was impregnated into the prepared microemulsion. After the emulsion was completely absorbed, the catalyst was dried at 120°C for 6 hours and calcined at 550°C for 3 hours to obtain the semi-finished catalyst M.

[0101] (2) Weigh 6.52 g of ferric nitrate and dissolve it in 48 g of deionized water. Then add the semi-finished catalyst M to the prepared Fe salt solution. After the solution is completely absorbed, age it for 1 hour, dry it at 100°C, and calcine it at 350°C for 8 hours to obtain the semi-finished catalyst N.

[0102] (3) 13.33 mg of palladium chloride was weighed and dissolved in 48 g of deionized water, and the pH was adjusted to 2.2. The semi-finished catalyst N was then added to the prepared Pd salt solution, aged for 12 hours, dried at 100°C, and calcined at 450°C for 6 hours to obtain the semi-finished catalyst O;

[0103] (4) 8.33 mg of palladium chloride was weighed and dissolved in 40 ml of deionized water. 10 g of cyclohexane, 1.6 g of Triton X-100, and 1.6 g of n-butanol were added and stirred thoroughly to form a microemulsion. The semi-finished catalyst O was impregnated into the prepared microemulsion. After impregnation for 4 hours, the remaining liquid was filtered off. The catalyst was washed with deionized water until neutral, dried at 120° C. for 6 hours, and calcined at 450° C. for 6 hours to obtain the desired catalyst.

[0104] The particle size of the microemulsion prepared in steps (1) and (4) was 400 nm as determined by dynamic light scattering.

[0105] The prepared catalyst was measured by atomic absorption spectrometry. Based on the support as 100%, in Example 4, the Pd content was 0.013%, the Ni content was 1.5%, and the Fe content was 1.5%. The Pd content in the solution method was 0.008%, and the Pd content in the emulsion method was 0.005%.

[0106] Before use, it was placed in a fixed bed reaction device and reduced with a mixed gas with a molar ratio of N2:H2=1:1 at a temperature of 220°C for 12 hours.

[0107] Comparative Example 4 Comparative Example 4 provides a catalyst using the same carrier as in Example 4. The catalyst preparation conditions are also the same, except that the emulsion method does not support Pd.

[0108] Catalyst preparation:

[0109] (1) 4.67 g of nickel nitrate was dissolved in 40 ml of deionized water, and 10 g of cyclohexane, 1.6 g of Triton X-100, and 1.23 ml of n-butanol were added and stirred thoroughly to form a microemulsion. 100 g of the carrier was impregnated into the prepared microemulsion. After the emulsion was completely absorbed, the catalyst was dried at 120°C for 6 hours and calcined at 550°C for 3 hours to obtain the semi-finished catalyst M.

[0110] (2) Weigh 6.52 g of ferric nitrate and dissolve it in 48 g of deionized water. Then add the semi-finished catalyst M to the prepared Fe salt solution. After the solution is completely absorbed, age it for 1 hour, dry it at 100°C, and calcine it at 350°C for 8 hours to obtain the semi-finished catalyst N.

[0111] (3) Weigh 13.33 mg of palladium chloride and dissolve it in 48 g of deionized water. Adjust the pH to 2.2. Then add the semi-finished catalyst N to the prepared Pd salt solution. Aged for 12 hours, dried at 100°C, and calcined at 450°C for 6 hours to obtain the desired catalyst.

[0112] The particle size of the microemulsion prepared in step (1) was determined to be 400 nm by dynamic light scattering.

[0113] The prepared catalyst was measured by atomic absorption spectrometry. Based on the support as 100%, in Comparative Example 4, the Pd content was 0.008%, the Ni content was 1.5%, and the Fe content was 1.5%.

[0114] Before use, it was placed in a fixed bed reaction device and reduced with a mixed gas with a molar ratio of N2:H2=1:1 at a temperature of 220°C for 12 hours.

[0115] Example 5

[0116] Support: A commercially available bimodal pore distribution spherical alumina support with an alumina content of 95%, a titanium oxide content of 5%, and a diameter of 3.5 mm. After calcination at 1310°C, the specific surface area is 10 m 2 / g, water absorption rate 44%, small pore diameter 40-65nm, large pore diameter 390-540nm, weighing 100g of the carrier. After high-temperature roasting for 4h, weighing 100g of the carrier.

[0117] Catalyst preparation:

[0118] (1) Weigh 4.42 g of nickel chloride and dissolve it in 40 ml of deionized water. Add 15.38 g of cyclohexane, 5.38 g of Triton X-10, and 3.85 ml of n-butanol, and stir thoroughly to form a microemulsion. Then, soak 100 g of the carrier in the prepared microemulsion. After the emulsion is completely absorbed, dry it at 120°C for 6 hours and calcine it at 450°C for 5 hours to obtain a semi-finished catalyst P.

[0119] (2) Weigh 5.22 g of ferric nitrate and dissolve it in 44 g of deionized water. Then add the semi-finished catalyst P to the prepared Fe salt solution. After the solution is completely absorbed, age it for 4 hours, dry it at 110° C., and calcine it at 600° C. for 2 hours to obtain the semi-finished catalyst Q.

[0120] (3) 16.67 mg of palladium chloride was weighed and dissolved in 44 g of deionized water, and the pH was adjusted to 1.9. The semi-finished catalyst Q was then added to the prepared Pd salt solution. After the solution was completely absorbed, the catalyst was aged for 12 hours, dried at 100° C., and calcined at 400° C. for 8 hours to obtain the semi-finished catalyst R.

[0121] (4) Weigh 17.32 mg of palladium nitrate and dissolve it in 40 ml of deionized water. Add 15.38 g of cyclohexane, 5.38 g of Triton X-10, and 3.85 g of n-butanol to the 40 ml of deionized water and stir thoroughly to form a microemulsion. Then, impregnate the semi-finished catalyst R into the prepared microemulsion. After the emulsion is completely absorbed, dry it at 120°C for 6 hours and calcine it at 480°C for 6 hours to obtain the desired catalyst.

[0122] The particle size of the microemulsion prepared in steps (1) and (4) was determined to be 100 nm by dynamic light scattering.

[0123] The prepared catalyst was measured by atomic absorption spectrometry. Based on the support as 100%, in Example 5, the Pd content was 0.018%, the Ni content was 2.0%, and the Fe content was 1.2%. The Pd content in the solution method was 0.008%, and the Pd content in the emulsion method was 0.010%.

[0124] Before use, it was placed in a fixed bed reaction device and reduced with a mixed gas with a molar ratio of N2:H2=1:1 at a temperature of 190°C for 12 hours.

[0125] Comparative Example 5

[0126] The same carrier and catalyst preparation process as in Example 5 were used, with the only difference being the particle size of the microemulsion in step (4).

[0127] Catalyst preparation:

[0128] (1) Weigh 4.42 g of nickel chloride and dissolve it in 40 ml of deionized water. Add 15.38 g of cyclohexane, 5.38 g of Triton X-10, and 3.85 ml of n-butanol, and stir thoroughly to form a microemulsion. Then, soak 100 g of the carrier in the prepared microemulsion. After the emulsion is completely absorbed, dry it at 120°C for 6 hours and calcine it at 450°C for 5 hours to obtain a semi-finished catalyst P.

[0129] (2) Weigh 5.22 g of ferric nitrate and dissolve it in 44 g of deionized water. Then add the semi-finished catalyst P to the prepared Fe salt solution. After the solution is completely absorbed, age it for 4 hours, dry it at 110° C., and calcine it at 600° C. for 2 hours to obtain the semi-finished catalyst Q.

[0130] (3) 16.67 mg of palladium chloride was weighed and dissolved in 44 g of deionized water, and the pH was adjusted to 1.9. The semi-finished catalyst Q was then added to the prepared Pd salt solution. After the solution was completely absorbed, the catalyst was aged for 12 hours, dried at 100° C., and calcined at 400° C. for 8 hours to obtain the semi-finished catalyst R.

[0131] (4) Weigh 17.32 mg of palladium nitrate and dissolve it in 40 ml of deionized water. Add 9.52 g of cyclohexane, 1.14 g of Triton X-10, and 0.816 g of n-butanol to the 40 ml of deionized water and stir thoroughly to form a microemulsion. Then, impregnate the semi-finished catalyst R into the prepared microemulsion. After the emulsion is completely absorbed, dry it at 120°C for 6 hours and calcine it at 480°C for 6 hours to obtain the desired catalyst.

[0132] The particle size of the microemulsion prepared in step (1) was 100 nm as determined by dynamic light scattering, and the particle size of the microemulsion prepared in step (4) was 700 nm.

[0133] The prepared catalyst was measured by absorption spectroscopy. Calculated based on the support as 100%, in Comparative Example 5, the Pd content was 0.018%, the Ni content was 2.0%, and the Fe content was 1.2%. The Pd content loaded by the solution method was 0.008%, and the Pd content loaded by the emulsion method was 0.010%.

[0134] Before use, it was placed in a fixed bed reaction device and reduced with a mixed gas with a molar ratio of N2:H2=1:1 at a temperature of 190°C for 12 hours.

[0135] Example 6

[0136] Carrier: A commercially available bimodal pore distribution spherical carrier with a diameter of 4 mm was used. After calcination at 1325°C, the specific surface area was 12 m 2 / g, water absorption rate 47%, small pore diameter of 40-60nm, large pore diameter of 200-580nm, and 100g of the carrier is weighed.

[0137] Catalyst preparation:

[0138] (1) Weigh 2.92 g of ferric chloride and dissolve it in 47 g of deionized water. Then, weigh 100 g of the carrier and add it to the prepared Fe salt solution. After the solution is completely absorbed, age it for 6 hours, dry it at 120° C., and calcine it at 250° C. for 8 hours to obtain a semi-finished catalyst S.

[0139] (2) Weigh 3.11 g of nickel nitrate and dissolve it in 40 ml of deionized water. Add 15.38 g of n-hexane, 6.15 g of CTAB, and 5.59 g of n-octanol, and stir thoroughly to form a microemulsion. Then, impregnate the semi-finished catalyst S into the prepared microemulsion. After the emulsion is completely absorbed, dry it at 80°C and calcine it at 400°C for 8 h to obtain the semi-finished catalyst T.

[0140] (3) Weigh 25 mg of palladium chloride and dissolve it in 47 g of deionized water, adjust the pH to 2.5, then add the semi-finished catalyst T to the Pd salt solution, age it for 10 hours, dry it at 120°C, and calcine it at 420°C for 4 hours to obtain the semi-finished catalyst U;

[0141] (4) Weigh 11.17 mg of palladium chloride and dissolve it in 40 ml of deionized water. Add 15.38 g of n-hexane, 6.15 g of CTAB, and 5.59 g of n-octanol and stir thoroughly to form a microemulsion. Then, impregnate the semi-finished catalyst U into the prepared microemulsion. After the emulsion is completely absorbed, dry it at 80°C and calcine it at 520°C for 4 hours to obtain the desired catalyst.

[0142] The particle size of the microemulsion prepared in steps (2) and (4) was 200 nm as determined by dynamic light scattering.

[0143] The prepared catalyst was measured by atomic absorption spectrometry. Based on the support as 100%, the Pd content in Example 6 was 0.0217%, the Ni content was 1.0%, and the Fe content was 1.0%. The Pd content in the solution method was 0.015%, and the Pd content in the emulsion method was 0.0067%.

[0144] Before use, it was placed in a fixed bed reactor and reduced with pure hydrogen at 200°C for 8 hours.

[0145] Comparative Example 6 provides a catalyst, the carrier of which is the same as that of Example 6, and the catalyst preparation conditions are the same, except that Pd is loaded first and then Fe is loaded by the solution method.

[0146] Catalyst preparation:

[0147] (1) Weigh 25 mg of palladium chloride and dissolve it in 47 g of deionized water. Adjust the pH to 2.5. Add 100 g of the carrier to the Pd salt solution. After the solution is completely absorbed, dry it at 120° C. and calcine it at 420° C. for 4 hours to obtain a semi-finished catalyst S1.

[0148] (2) Weigh 3.11 g of nickel nitrate, dissolve it in 40 ml of deionized water, add 15.38 g of n-hexane, 6.15 g of CTAB, and 5.59 g of n-octanol, and stir thoroughly to form a microemulsion. Then, impregnate the semi-finished catalyst S1 into the prepared microemulsion. After the emulsion is completely absorbed, dry it at 80°C and calcine it at 400°C for 8 h to obtain the semi-finished catalyst T1.

[0149] (3) Weigh 2.92 g of ferric chloride and dissolve it in 47 g of deionized water. Then, add the semi-finished catalyst T to the prepared Fe salt solution and age it for 10 hours, age it for 6 hours, dry it at 120° C., and calcine it at 250° C. for 8 hours to obtain the semi-finished catalyst U1.

[0150] (4) Weigh 11.17 mg of palladium chloride and dissolve it in 40 ml of deionized water. Add 15.38 g of n-hexane, 6.15 g of CTAB, and 5.59 g of n-octanol and stir thoroughly to form a microemulsion. Then, impregnate the semi-finished catalyst U1 into the prepared microemulsion. After the emulsion is completely absorbed, dry it at 80°C and calcine it at 520°C for 4 hours to obtain the desired catalyst.

[0151] The particle size of the microemulsion prepared in steps (2) and (4) was 200 nm as determined by dynamic light scattering.

[0152] The prepared catalyst was measured by atomic absorption spectrometry. Based on the support as 100%, the Pd content in Example 6 was 0.0217%, the Ni content was 1.0%, and the Fe content was 1.0%. The Pd content in the solution method was 0.015%, and the Pd content in the emulsion method was 0.0067%.

[0153] Before use, it was placed in a fixed bed reactor and reduced with pure hydrogen at 200°C for 8 hours.

[0154] Example 7

[0155] Support: Commercially available bimodal pore distribution spherical alumina support with a diameter of 4 mm. Calcinated at 1310°C, with a specific surface area of ​​12 m 2 / g, water absorption rate 46%, small pore diameter 40 ~ 60nm, large pore diameter 200 ~ 580nm, weigh the carrier 100g

[0156] Catalyst preparation:

[0157] (1) 7.47 g of nickel nitrate was weighed and dissolved in 42 ml of deionized water. 12 g of n-hexane, 3.24 g of CTAB, and 2.95 g of n-pentanol were added and stirred thoroughly to form a microemulsion. 100 g of the support was impregnated into the prepared microemulsion for 0.5 h, washed with deionized water until neutral, dried at 80 °C, and calcined at 400 °C for 8 h to obtain a semi-finished catalyst V.

[0158] (2) Weigh 6.52 g of ferric nitrate and dissolve it in 47 g of deionized water. Then add the semi-finished catalyst V to the prepared Fe salt solution. After the solution is completely absorbed, age it for 6 hours, dry it at 120° C., and calcine it at 400° C. for 8 hours to obtain the semi-finished catalyst W.

[0159] (3) 13.33 mg of palladium chloride was weighed and dissolved in 47 g of deionized water, and the pH was adjusted to 2.3. The semi-finished catalyst W was then added to the Pd salt solution, aged for 10 hours, dried at 120° C., and calcined at 530° C. for 4 hours to obtain the semi-finished catalyst X;

[0160] (4) 12.99 mg of palladium nitrate was weighed and dissolved in 42 ml of deionized water. 12 g of n-hexane, 3.24 g of CTAB, and 2.95 g of n-pentanol were added and stirred thoroughly to form a microemulsion. The semi-finished catalyst X was impregnated into the prepared microemulsion for 0.5 hour, washed with deionized water until neutral, dried at 80°C, and calcined at 520°C for 4 hours to obtain the desired catalyst.

[0161] The particle size of the microemulsion prepared in steps (1) and (4) was 200 nm as determined by dynamic light scattering.

[0162] The prepared catalyst was measured by atomic absorption spectrometry. Based on the support as 100%, in Example 6, the Pd content was 0.016%, the Ni content was 2.4%, and the Fe content was 2.0%. The Pd content was 0.008% for the solution method and 0.008% for the emulsion method.

[0163] Before use, it was placed in a fixed bed reactor and reduced with pure hydrogen at 210°C for 8 hours.

[0164] Comparative Example 7 This comparative example provides a catalyst, whose carrier is the same as that in Example 7 and the catalyst preparation conditions are the same, except that in Comparative Example 7, Pd is first loaded by the emulsion method.

[0165] (1) Weigh 12.99 mg of palladium nitrate, dissolve it in 42 ml of deionized water, add 12 g of n-hexane, 3.24 g of CTAB, and 2.95 g of n-pentanol, and stir thoroughly to form a microemulsion. Then, soak 100 g of the carrier in the prepared microemulsion. After the emulsion is completely absorbed, dry it at 80°C and calcine it at 520°C for 4 hours to obtain a semi-finished catalyst V1.

[0166] (2) Weigh 6.52 g of ferric nitrate and dissolve it in 47 g of deionized water. Then add the semi-finished catalyst V1 to the prepared Fe salt solution. After the solution is completely absorbed, age it for 6 hours, dry it at 120° C., and calcine it at 400° C. for 8 hours to obtain the semi-finished catalyst W1.

[0167] (3) 13.33 mg of palladium chloride was weighed and dissolved in 47 g of deionized water, and the pH was adjusted to 2.3. The semi-finished catalyst W1 was then added to the Pd salt solution, aged for 10 hours, dried at 120°C, and calcined at 530°C for 4 hours to obtain the semi-finished catalyst X1;

[0168] (4) 7.47 g of nickel nitrate was weighed and dissolved in 42 ml of deionized water. 12 g of n-hexane, 3.24 g of CTAB, and 2.95 g of n-pentanol were added and stirred thoroughly to form a microemulsion. The semi-finished catalyst X1 was impregnated into the prepared microemulsion. After the emulsion was completely absorbed, the mixture was dried at 80°C and calcined at 400°C for 8 h to obtain the desired catalyst.

[0169] The particle size of the microemulsion prepared in steps (1) and (4) was 200 nm as determined by dynamic light scattering.

[0170] The prepared catalyst was measured by atomic absorption spectrometry. Based on the support as 100%, in Example 6, the Pd content was 0.016%, the Ni content was 2.4%, and the Fe content was 2.0%. The Pd content was 0.008% for the solution method and 0.008% for the emulsion method.

[0171] Before use, it was placed in a fixed bed reactor and reduced with pure hydrogen at 210°C for 8 hours.

[0172] Example 8

[0173] Support: Commercially available bimodal pore distribution spherical alumina support with a diameter of 3.5 mm, calcined at 110 ° C, with a specific surface area of ​​10 m 2 / g, water absorption rate 45%, small pore diameter 50-70nm, large pore diameter 300-650nm, weigh 100g of the carrier.

[0174] (1) Weigh 2.33 g of ferric chloride and dissolve it in 45 g of deionized water. Add 100 g of the calcined carrier to the prepared Fe salt solution. After the solution is completely absorbed, age for 4 hours, dry at 100° C., and calcine at 280° C. for 6 hours to obtain a semi-finished catalyst AA.

[0175] (2) 6.23 g of nickel nitrate was dissolved in 45 ml of deionized water, and 17.31 g of n-hexane, 6.06 g of CTAB, and 4.33 g of n-octanol were added and stirred thoroughly to form a microemulsion. The semi-finished catalyst AA was impregnated into the prepared microemulsion. After the emulsion was completely absorbed, the mixture was dried at 100° C. and calcined at 520° C. for 5 h to obtain the semi-finished catalyst AB.

[0176] (3) 10.82 mg of palladium nitrate was weighed and dissolved in 45 g of deionized water, and the pH was adjusted to 1.6. The semi-finished catalyst AB was then added to the Pd salt solution, aged for 10 hours, dried at 60°C, and calcined at 480°C for 4 hours to obtain the semi-finished catalyst AC;

[0177] (4) 32.47 mg of palladium nitrate was weighed and dissolved in 45 ml of deionized water. 17.31 g of n-hexane, 6.06 g of CTAB, and 4.33 g of n-octanol were added and stirred thoroughly to form a microemulsion. The semi-finished catalyst AC was impregnated into the prepared microemulsion. After the emulsion was completely absorbed, the catalyst was dried at 80°C and calcined at 420°C for 4 hours to obtain the desired catalyst.

[0178] The particle size of the microemulsion prepared in steps (2) and (4) was determined to be 100 nm by dynamic light scattering.

[0179] The prepared catalyst was measured by atomic absorption spectrometry. Based on the support as 100%, in Example 2, the Pd content was 0.020%, the Ni content was 2.0%, and the Fe content was 0.8%. The Pd content in the solution method was 0.015%, and the Pd content in the emulsion method was 0.005%.

[0180] Performance of catalysts used in C2 post-hydrogenation reaction

[0181] Evaluation test 1: Reaction conditions: the catalyst loading amount in the fixed bed single-stage reactor is 100 mL, the reaction material space velocity is 10,000 / h, the operating pressure is 3.4 MPa, and the initial inlet temperature of the reactor is 100°C.

[0182] Reaction requirements: acetylene conversion rate of more than 65% and selectivity of more than 80% in the first stage.

[0183] The composition of the reaction materials is shown in Table 1.

[0184] Table 1 Reaction material composition

[0185]

[0186] Table 2 Catalyst evaluation results

[0187]

[0188] Compared with Example 1, Comparative Example 1 does not have Ni loaded in the comparative example, and the macropores of the catalyst have basically no hydrogenation function for the hydrogenation by-product butadiene. After 1000 hours, the activity and selectivity decrease significantly.

[0189] In Comparative Example 2, no Fe is loaded, and only a very small amount of Pd is present in the pores, resulting in a very low acetylene hydrogenation activity.

[0190] In Comparative Example 3, the solution method did not load Pd, and the activity of Fe at this content was very low because its ability to adsorb hydrogen was poor, resulting in a significant difference in acetylene conversion from that in Example.

[0191] In Comparative Example 4, the microemulsion method did not load Pd. At a temperature of about 200°C, Ni was not effectively reduced and could not effectively play a role in saturated hydrogenation of the reaction by-products. It is possible that only a small amount of by-products underwent saturated hydrogenation on the surface of the Pd active center. The amount of catalyst coking was significantly higher than that of the embodiment. The selectivity of the catalyst in the comparative example decreased by 5 percentage points after 1000 hours, and the selectivity decreased by 9 percentage points, while the selectivity of the catalyst in Example 4 only decreased by 1 percentage point. That is, the deactivation rate of the catalyst in Comparative Example 4 was 9 times that of the catalyst in Example 4.

[0192] In Comparative Example 5, the microemulsion particle size when loaded with Pd was larger than the maximum pore size of the support macropores. The microemulsion could not effectively enter the macropores and was only loaded on the outermost surface of the catalyst, partially contributing to acetylene hydrogenation or interacting with Ni to saturate hydrogenation of a small amount of byproducts. Consequently, the activity and selectivity after 1000 hours were significantly lower than those in Example 5. Because the Pd loaded in the microemulsion was located on the outer surface of the catalyst, although the Fe loading in Comparative Example 5 was significantly lower than that in Comparative Example 4, its initial acetylene hydrogenation activity was comparable to that of Comparative Example 4.

[0193] In Comparative Example 6, Pd was first loaded by the solution method. This small amount of Pd was covered by the subsequently loaded Fe and could not provide hydrogen for the Fe active center in the reaction. The activity of acetylene hydrogenation was very low.

[0194] In Comparative Example 7, the Pd loaded first by the emulsion method is covered by the Ni loaded later by the emulsion method, and cannot effectively reduce the Ni reduction temperature. The saturated hydrogenation reaction of the by-products cannot occur, and the catalyst selectivity decrease rate is much faster than that of the catalyst in Example 7.

[0195] In Comparative Example 8, the support's specific surface area is twice that of Example 8, and the active component loading area is significantly larger than that of Example 8. This results in insufficient activity at both active centers in the comparative example catalyst. This leads to a low initial acetylene conversion rate and insufficient activity at the saturated hydrogenation centers, resulting in a faster decline in activity and selectivity after 1000 hours than in Example 8.

[0196] Evaluation Test 2

[0197] The test sample is the catalyst of Example 8.

[0198] Material composition: Same as Experiment 1, except that CO was added separately, and the rate of change of its content was: from 0.04% (v) to 0.15% (v) within 15 minutes.

[0199] Sampling and analysis method: Analyze once before CO content adjustment, analyze once after CO content adjustment, and perform a second sampling and analysis 15 minutes later.

[0200] Reaction conditions: the catalyst loading amount in the fixed bed two-stage reactor is 300 mL, the catalyst reaction material space velocity is 12000 / h, the operating pressure is 3.6 MPa, the initial reactor inlet temperature is 105°C, and the second stage temperature is 120°C.

[0201] The evaluation results are shown in Table 3.

[0202] Table 3 Reaction material composition and evaluation results

[0203]

[0204] The results in Table 3 show that, while the contents of other components in the hydrogenation feed remained essentially unchanged, CO was increased from 0.05% (v) to 0.15% (v) within 15 minutes, a two-fold increase. This represents a near-maximum increase from the lowest possible concentration, and is within the maximum range achievable by a commercial plant. Before the CO content was increased, the first-stage acetylene conversion was 92.4%, with complete conversion of acetylene in the second stage. After the CO content was increased, the first-stage acetylene conversion decreased by 10 percentage points, while the selectivity increased by 4 percentage points. The second-stage acetylene conversion remained at 100%. A repeat test was conducted 15 minutes later, and the results were comparable to those of the initial analysis after the CO change.

[0205] The results show that while a rapid and substantial increase in CO content does affect the hydrogenation activity of the first-stage catalyst of the present invention, the magnitude of this change is minimal compared to that of precious metal catalysts. Furthermore, the second-stage catalyst can still fully convert acetylene, demonstrating that even with CO levels reaching nearly the maximum possible level, the catalyst of the present invention can still achieve zero acetylene leakage. This is a significant advantage over conventional catalysts.

Claims

1. A selective hydrogenation catalyst for C1-C3 fractions, wherein the catalyst carrier has a bimodal pore distribution structure, characterized in that: The catalyst contains at least Pd, Ni and Fe; wherein Pd is loaded by a microemulsion method and a solution method, and the particle size of the Pd in ​​the microemulsion is greater than 80 nm and less than 800 nm; Ni is loaded by a microemulsion method, and the particle size of the Ni in the microemulsion is greater than 80 nm and less than 800 nm; Fe is loaded by a solution method; based on the mass of the carrier being 100%, the total content of Pd loaded by the microemulsion method and the solution method is 0.009-0.0245%, wherein the content of Pd loaded by the solution method is 0.007-0.015%, and the ratio of Pd loaded by the solution method to Fe loaded by the solution method is 0.004-0.024:1; the content of Ni is 1.0-2.5%; and the content of Fe is 0.5-1.5%. In the bimodal pore distribution structure, the pore diameter of the small pores is 30 to 80 nm, and the pore diameter of the large pores is 130 to 800 nm; The specific surface area of ​​the selective hydrogenation catalyst of the C1-C3 fraction is 3-15m 2 / g; In the method for preparing the selective hydrogenation catalyst for the C1-C3 fraction, nickel and iron are first loaded, and then palladium is loaded.

2. The method for preparing the selective hydrogenation catalyst for C1-C3 fraction according to claim 1, characterized in that: include: (1) The carrier is added to a Ni microemulsion for impregnation, and after calcination, an aqueous solution of an Fe precursor salt is added for impregnation and calcination; or, the carrier is added to an aqueous solution of an Fe precursor salt, and after calcination, the carrier is added to a Ni microemulsion for impregnation and calcination; the Ni microemulsion is formed by adding an oil phase, a surfactant and a cosurfactant to the aqueous solution of the Ni precursor salt and stirring, and the particle size of the microemulsion is greater than 80 nm and less than 800 nm; (2) adding the product prepared in step (1) to an aqueous solution of a Pd precursor salt, aging, drying, and roasting, and then adding a Pd microemulsion for impregnation and roasting; or, adding the product prepared in step (1) to a Pd microemulsion for impregnation and roasting, and then adding it to an aqueous solution of a Pd precursor salt for aging, drying, and roasting; the Pd microemulsion is formed by adding an oil phase, a surfactant, and a cosurfactant to an aqueous solution of a Pd precursor salt and stirring, and the particle size of the microemulsion is greater than 80 nm and less than 800 nm.

3. The method according to claim 2, characterized in that In step (1), the oil phase is an alkane, the surfactant is Triton X-100 or CTAB, and the co-surfactant is an alcohol.

4. The method according to claim 3, characterized in that The oil phase in step (1) is cyclohexane or n-hexane, and the co-surfactant is n-butanol, n-pentanol or n-octanol.

5. The method according to claim 2, characterized in that: In step (2), the oil phase is an alkane, the surfactant is Triton X-100 or CTAB, and the co-surfactant is an alcohol.

6. The method according to claim 5, characterized in that The oil phase in step (2) is cyclohexane or n-hexane, and the co-surfactant is n-butanol, n-pentanol or n-octanol.

7. The method according to claim 2, characterized in that: In the steps (1) and (2), the mass ratio of water in the aqueous solution to the oil phase is 2.5 to 4.5:1; the mass ratio of the surfactant to the oil phase is 0.1 to 0.4:1; and the mass ratio of the surfactant to the co-surfactant is 1.0 to 1.40:

1.

8. The method according to claim 2, characterized in that: The calcination temperature in step (1) is 400-600°C.

9. The method according to claim 2, characterized in that: The calcination temperature in step (2) is 250-600°C.

10. A carbon dihydrogenation process, characterized in that: The selective hydrogenation catalyst for the C1-C3 fraction according to claim 1 is used.

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