A selective hydrogenation process for a pyrolysis gasoline fraction

Abstract

This invention provides a selective hydrogenation method for cracked gasoline fractions, in which the cracked gasoline fractions and hydrogen are hydrogenated in a fixed-bed reactor at a temperature of 30–100°C, a pressure of 2.0–5.0 MPa, and a feed volume hourly space velocity of 0.8–3.5 h⁻¹. ‑1 The hydrogen-to-oil volume ratio is 80–300:1; the catalyst support is alumina with a bimodal porous structure; the active components include Pd, Pt, Ce, W, Ni, and Cu, with Pd content of 0.2–0.5%, Pt content of 0.02–0.15%, Ce content of 0.5–4.0%, W content of 0.2–2.5%, Ni content of 0.5–5.0%, and Cu content of 0.5–3.0% by catalyst mass. Ni-Cu is supported by a microemulsion method, while Pd, Pt, Ce, and W are supported by a solution method, with Pt and Ce being supported simultaneously. This hydrogenation method exhibits excellent hydrogenation activity, anti-coking properties, and regeneration performance.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of petrochemical industry, and particularly relates to a selective hydrogenation method of cracking gasoline fraction. BACKGROUND

[0002] Cracking gasoline is an important by-product of the ethylene industry, accounting for 50wt% to 80wt% of the ethylene production capacity, and the content of aromatic hydrocarbons in cracking gasoline is as high as 50% or more, which is an important raw material for extracting aromatic hydrocarbons. Cracking gasoline contains a large amount of unsaturated hydrocarbons (diene, monoene) and impurities such as sulfur and nitrogen, resulting in poor stability of cracking gasoline, which is prone to form gum, and these unsaturated hydrocarbons and impurities such as sulfur and nitrogen can greatly reduce the selectivity of the extractant during the extraction of aromatic hydrocarbons, and seriously affect the purity and color of the aromatic hydrocarbon product. Therefore, cracking gasoline must be subjected to hydrofining to remove olefins and impurities such as sulfur and nitrogen before being used as a raw material for aromatic hydrocarbon extraction. At present, two-stage hydrofining technology is generally used at home and abroad to remove olefins and impurities such as sulfur and nitrogen in cracking gasoline, so as to produce qualified aromatic hydrocarbon extraction raw materials.

[0003] The first-stage hydrogenation is mainly to selectively hydrogenate diene olefins and chain alkenyl aromatic hydrocarbons into monoene olefins and alkyl aromatic hydrocarbons under low-temperature conditions; the second-stage hydrogenation belongs to a full hydrogenation reaction, which removes the remaining olefins and impurities such as sulfur and nitrogen under high-temperature conditions, and the hydrogenated product is sent to a downstream aromatic hydrocarbon extraction device for further rectification to separate benzene, toluene and xylene products.

[0004] Hydrogenation catalyst technology is a key technology for the aromatic hydrocarbon extraction process. At present, the first-stage selective hydrogenation of cracking gasoline in the industry mainly uses Pd / Al2O3 or Ni / Al2O3 system catalysts. Among them, the palladium-based catalyst has the advantages of low start-up temperature, high hydrogenation activity, high space velocity, long running period, strong regeneration capacity and the like.

[0005] In recent years, under the background of rapid expansion of ethylene production capacity and enterprises' quality improvement and efficiency enhancement, the cracking gasoline hydrogenation technology is facing new challenges: ① The upstream ethylene device tends to be large-scale, and the cracking raw material tends to be diversified, resulting in an increase in the load of the downstream cracking gasoline device, complex and variable composition of the raw material, and an increase in the content of impurities; ② Enterprises require the catalyst to be stably operated for more than 4 years for quality improvement and efficiency enhancement. Therefore, higher requirements are put forward for the hydrogenation activity, selectivity, anti-impurity performance and running stability of the cracking gasoline catalyst.

[0006] In view of the new challenges faced by the pyrolysis gasoline hydrogenation technology, the palladium-based catalysts in the prior art have been improved. For example, Chinese Patent Document CN200810114744.0 discloses an unsaturated hydrocarbon selective hydrogenation catalyst and a preparation method thereof. The catalyst comprises the following components based on the total weight of the catalyst: palladium as the active component, the content of palladium being 0.1-1.0%, the content of rare earth metal being 0.1-6.0%, the content of alkaline earth metal being 0.1-4.0%, and the catalyst can further contain fluorine, the content of fluorine being 0-3.0%, and the balance being the alumina carrier. The alumina carrier is θ or mixed crystal Al2O3, mainly θ crystal. The catalyst is suitable for the selective hydrogenation process of full-range pyrolysis gasoline in the first stage, and is also suitable for the selective hydrogenation process of unsaturated hydrocarbons in other distillate oils. Although the catalyst improves the resistance to impurities and coking performance by adding rare earth and alkaline earth metal and fluorine, the selectivity of the catalyst is not ideal.

[0007] Chinese Patent Document CN200810119385.8 discloses a non-noble metal supported selective hydrogenation catalyst, a preparation method and application thereof. The catalyst comprises a carrier and a main active component and an auxiliary active component supported on the carrier. The main active component is Ni, and the auxiliary active component is selected from at least one of Mo, La, Ag, Bi, Cu, Nd, Cs, Ce, Zn and Zr. The main active component and the auxiliary active component both exist in an amorphous state, and the average particle size is <10 nm. The carrier is a non-oxidizing porous material. The catalyst is prepared by a microemulsion method and is used in the removal of alkyne in carbon two selective hydrogenation reaction, but the selectivity of the catalyst needs to be further improved.

[0008] Chinese Patent Document CN201110234140.1 provides a hydrogenation catalyst comprising an alumina-titanium oxide composite carrier and metal palladium and metal molybdenum or metal tungsten supported on the composite carrier. The weight ratio of alumina to titanium oxide in the composite carrier is 3:1-6:1. The content of metal palladium is 0.2-0.4% based on the weight of the catalyst. The weight ratio of metal palladium to metal molybdenum or to metal tungsten is 1:0.8-2. The catalyst is used for the hydrogenation of carbon five petroleum resin. However, the hydrogenation stability of the catalyst needs to be further improved.

[0009] Chinese patent document CN201310114077.7 discloses a hydrogenation catalyst, the active component of which contains Pd, Ag, and Ni, wherein Pd and Ag are loaded by impregnation with an aqueous solution, and Ni is loaded by impregnation with a W / O microemulsion. After this method, Pd / Ag and Ni are located in different pore channels of different pore sizes, and the green oil produced in the reaction is saturated hydrogenated in the large pores, and the amount of catalyst coking is reduced. However, the reduction temperature of Ni often reaches about 500°C, and at this temperature, the Pd atoms in the reduced state are prone to aggregation, which greatly reduces the activity of the catalyst, and the amount of active components needs to be greatly increased to compensate for the loss of activity, but this will also cause a decrease in selectivity.

[0010] Chinese patent document CN202010815254.4 discloses a selective hydrogenation catalyst, the carrier of which is alumina or mainly alumina and has a bimodal pore distribution structure. The content of Pd is 0.15-0.50wt% based on 100% of the mass of the catalyst, the mass ratio of Pd to W is 1-5:1, the content of Ni is 0.5-5wt%, and the mass ratio of Cu to Ni is 0.1-1:1. Ni and Cu are loaded in the large pores of the carrier by a microemulsion method, W is loaded by a solution method, and Pd is loaded by both a solution method and a microemulsion method. When this catalyst is used for the selective hydrogenation of a pyrolysis gasoline fraction, it has good hydrogenation activity, excellent selectivity, and high coking resistance. However, in order to reduce the reduction temperature of the Ni active center, copper and a small amount of palladium are added by the emulsion method. Since palladium is loaded twice, the content of palladium in the catalyst is therefore higher than that in commonly used catalysts, and can be up to 50% higher, which greatly increases the cost of the catalyst.

[0011] Chinese patent document CN201811182796.1 discloses a method for the selective hydrogenation of full-range pyrolysis gasoline, which uses a fixed-bed reactor to reduce the catalyst under a hydrogen atmosphere, adjusts the reaction process conditions after the reduction process is completed, and then feeds the full-range pyrolysis gasoline raw material oil to carry out selective hydrogenation reaction. The catalyst comprises a silica-alumina carrier and a metal active component, palladium, loaded on the carrier. The content of palladium is 0.15-0.45wt% based on the total weight of the catalyst. The silica-alumina carrier contains 0.1-12wt% of silica, 0.1-10wt% of nickel-doped lanthanum ferrite, and 0.05-6.8wt% of potassium. The mesopores of the carrier account for 3-75% of the total pores, and the macropores account for 1.5-60% of the total pores. The micropores, mesopores, and macropores of the carrier are unevenly distributed. The hydrogenation process conditions are as follows: the reaction inlet temperature is ≥50°C, the reaction pressure is 2.0-4.5MPa, the hydrogen / oil volume ratio is 60-400:1, and the liquid volume space velocity is 2.5-5.0h -1 .

[0012] Chinese patent document ZL201710409059.X relates to a method for selective hydrogenation of C6-C8 fraction, the catalyst comprising an alumina carrier with a large pore structure and a metal active component of palladium supported on the carrier, the content of palladium being 0.2-0.35 wt% based on the total weight of the catalyst, the alumina carrier with a large pore structure containing an auxiliary component of phosphorus and magnesium, the content of the auxiliary phosphorus and magnesium being 0.1-2.5 wt% and 0.1-2.5 wt% of P2O5 and MgO, respectively, based on the mass of the carrier; hydrogenation process conditions: reaction inlet temperature ≤ 45℃, reaction pressure 2.5-4.5 MPa, hydrogen / oil volume ratio 60-450; liquid volume space velocity 3.0-5.5 h -1 .

[0013] Chinese patent document CN200810102240.7 relates to a method for selective hydrogenation of pyrolysis gasoline fraction in one stage, using a palladium-based hydrogenation catalyst, the catalyst being provided for use after reduction, the hydrogenation process conditions being: liquid volume space velocity ≤ 5 h -1 , reactor inlet temperature 28-120℃, reaction pressure ≥ 2.4 MPa, hydrogen / oil volume ratio 50-500; the palladium-based hydrogenation catalyst used, with a θ-type alumina or a θ-type-based θ, α mixed crystal type alumina carrier, with metal palladium as the active component, containing, based on 100% of the weight of the catalyst, 0.2-0.5 wt% of the active component Pd, 2-8 wt% of the auxiliary lanthanum and / or cerium, and 2-8 wt% of the alkaline earth metal element; the catalyst, after coking and deactivation, can still be regenerated and provided for use. Under this application method and process condition, the catalyst has good hydrogenation performance.

[0014] Chinese patent document CN201811182822.0 relates to a method for selective hydrogenation of full-range pyrolysis gasoline, using an adiabatic bed reactor, the catalyst comprising a silicon-alumina carrier and a metal active component of palladium supported on the carrier, the content of palladium being 0.15-0.45 wt% based on the total weight of the catalyst, the silicon-alumina carrier containing 0.1-12 wt% of silicon oxide, 0.1-10 wt% of nickel-doped lanthanum ferrite, and 0.05-7.8 wt% of magnesium; hydrogenation process conditions: reaction inlet temperature ≥ 50℃, reaction pressure 2.0-4.5 MPa, hydrogen / oil volume ratio 60-450; liquid volume space velocity 3.0-5.0 h-1. The catalyst has good resistance to gum, strong resistance to arsenic, sulfur and water.

[0015] Chinese patent document CN201811182799.5 discloses a pyrolysis gasoline first-stage selective hydrogenation method, which adopts an adiabatic bed reactor, a nickel-based catalyst is reduced in the presence of hydrogen at 400-480 DEG C, and after temperature reduction and passivation, the catalyst is adjusted to the reaction process conditions: reaction inlet temperature 45-120 DEG C, reaction pressure 2.5-5.5 MPa, hydrogen / oil volume ratio 60-220:1, liquid volume space velocity 2.0-6.5 h -1 The catalyst comprises a silicon oxide-aluminum oxide carrier and metal active components nickel, molybdenum and potassium supported on the carrier, and is suitable for pyrolysis gasoline first-stage selective hydrogenation.

[0016] Chinese patent document CN201110332661.0 discloses a pyrolysis gasoline first-stage selective hydrogenation catalyst, a preparation method and application thereof. The metal active component of the catalyst is prepared by a microemulsion method and is supported on the carrier after reduction, the active component is a metal atom or a low-valence metal ion, the particle size of the main active component Pd is less than 10 nm, the particle size is controllable, uniform and has good dispersity. The preparation method is simple, easy to operate and has mild production conditions; the catalyst has high activity, good selectivity and good gum tolerance when applied to diene and styrene selective hydrogenation reactions.

[0017] Chinese patent document CN202010811630.2 provides a selective hydrogenation method. A fixed bed reactor is adopted, the reactor is loaded with a hydrogenation catalyst containing at least Pd, W, Ni and Cu with a bimodal pore size distribution structure, pyrolysis gasoline is mixed with hydrogen and preheated before entering the reactor, and the hydrogenation process conditions are: reaction temperature 30-120 DEG C, reaction pressure 2-6 MPa, space velocity 0.5-4 h -1 , hydrogen / oil volume ratio 100-600:1. Ni and Cu in the catalyst are loaded in a microemulsion manner, so that Ni and Cu are mainly distributed in the large pores of the carrier; W is loaded by a solution method, and Pd is loaded by a solution method and a microemulsion method, wherein, most of Pd is loaded by the solution method, and a small part of Pd is loaded by the microemulsion method. The hydrogenation method has the characteristics of high hydrogenation activity, good selectivity and strong running stability.

[0018] As can be seen from the above, in order to improve the selectivity and hydrogenation performance of the catalyst, the existing technology is mostly modified and prepared by adding silicon oxide, phosphorus, alkaline earth metals and other elements, but the hydrogenation activity and anti-coking performance of the catalyst need to be improved. SUMMARY

[0019] The purpose of the present application is to provide a selective hydrogenation method for pyrolysis gasoline fractions, which can improve the olefin hydrogenation activity, anti-coking performance and regeneration performance of the catalyst.

[0020] To achieve the above object, the present application adopts the following technical solutions:

[0021] A selective hydrogenation method of a pyrolysis gasoline fraction, comprising the following steps: after mixing the pyrolysis gasoline fraction with hydrogen, the mixture is introduced into a fixed bed reactor to perform a hydrogenation reaction, the hydrogenation reaction temperature is 30-100℃, the reaction pressure is 2.0-5.0MPa, the feed volume space velocity of fresh pyrolysis gasoline fraction is 0.5-3.5h -1 , and the hydrogen / oil volume ratio is 80-300:1; the hydrogen / oil volume ratio refers to the volume ratio of hydrogen to fresh pyrolysis gasoline fraction;

[0022] The catalyst used in the hydrogenation reaction comprises a carrier and an active component, the carrier comprises alumina, the specific surface area of the alumina carrier is 60-150m 2 / g, and has a bimodal pore distribution structure, wherein the pore size of small pores is 10-60nm, and the pore size of large pores is 100-500nm; the active component comprises Pd, Pt, Ce, W, Ni and Cu, the Pd content is 0.2wt%-0.5wt%, preferably 0.25wt%-0.45wt%, the Pt content is 0.02wt%-0.15wt%, preferably 0.05wt%-0.10wt%, the Ce content is 0.5wt%-4.0wt%, preferably 1.0wt%-3.0wt%, the W content is 0.2wt%-2.5wt%, preferably 0.6wt%-2.0wt%, the Ni content is 0.5wt%-5.0wt%, preferably 1.5wt%-3.5wt%, and the Cu content is 0.5wt%-3.0wt%, preferably 1.0wt%-2.5wt%; Ni-Cu is loaded by a microemulsion method, the microemulsion particle size is controlled to make Ni and Cu be distributed in the large pores of the carrier, Pd, Pt, Ce and W are all loaded by a solution method, and are mainly loaded in the small pores of the carrier, and Pt and Ce are loaded at the same time.

[0023] Optionally, in the selective hydrogenation method of the pyrolysis gasoline fraction provided by the present application, the hydrogenation reaction temperature is 35-70℃, the reaction pressure is 2.4-3.5MPa, the feed volume space velocity of fresh pyrolysis gasoline fraction is 1.0-3.0h -1 , and the hydrogen / oil volume ratio is 80-200:1.

[0024] Optionally, in the selective hydrogenation method of the pyrolysis gasoline fraction provided by the present application, the fixed bed reactor is an adiabatic reactor or an isothermal reactor; preferably, the fixed bed reactor is an adiabatic reactor.

[0025] Optionally, in the selective hydrogenation method of the pyrolysis gasoline fraction provided by the present application, the catalyst used is prepared by limiting the content of Ce to 0.5wt%-4.0wt%, at which content the Ce can form a single layer of cerium oxide or a discontinuous layer of cerium oxide molecules; and by limiting the content of Pt to 0.02wt%-0.15wt%, so that the Pt exists in the form of single atoms and is mainly loaded on the cerium oxide.

[0026] Optionally, in the selective hydrogenation method of the pyrolysis gasoline fraction provided by the present application, the catalyst carrier further contains other metal oxides in addition to the alumina, such as lithium oxide, titanium oxide, etc. The content of the alumina in the carrier recommended by the present application is 80wt%-100wt% based on the mass of the carrier.

[0027] Optionally, in the selective hydrogenation method of the pyrolysis gasoline fraction provided by the present application, the shape of the carrier is not particularly limited, and can be any one of a sphere, a cylinder, a trilobal shape, a quadrilobal shape, etc.

[0028] For hydrogenation reactions, the hydrogenation catalyst needs to be reduced before use to ensure that the active components exist in the metallic state, so that the catalyst has hydrogenation activity. Because activation is a high-temperature calcination process during the preparation of the catalyst, in this process, the metal salt is generally decomposed into metal oxide, and the oxide forms clusters, which are generally nanosized. Different oxides need to be reduced at different temperatures due to their different chemical properties, but for nanosized metals, a temperature of about 200°C is an important critical temperature, and above this temperature, the metal particles will significantly aggregate. Therefore, how to reduce the aggregation of the main active components during the reduction process, and thus avoid the decrease in the utilization rate of the active components and the decrease in the hydrogenation activity of the catalyst, is of great significance for hydrogenation catalysts.

[0029] The inventors have found through research that the selective hydrogenation reaction of dienes in the raw material occurs at the main active center composed of Pd and W, and the produced macromolecules such as gum are easy to enter the large pores of the catalyst. In the large pores of the catalyst, the Ni-Cu components are loaded, and the Ni-Cu has a saturation hydrogenation function, and the macromolecular compound components will undergo saturation hydrogenation reaction at the Ni-Cu active center. Because the double bonds are hydrogenated and saturated, the macromolecular components such as gum cannot undergo polymerization reaction or the polymerization reaction rate is greatly reduced, the chain growth reaction is terminated or delayed, and large molecular weight condensed ring compounds cannot be formed, which are easy to be carried out of the reactor by the material, so the degree of coking on the surface of the catalyst is greatly reduced, and the operating life of the catalyst is prolonged. The alumina in the catalyst carrier of the present application requires a bimodal pore distribution structure, and in particular, has large pores with a pore size of 100-500nm and small pores with a pore size of 10-60nm.

[0030] The method for controlling the location of Ni-Cu in the macropores of the catalyst in the present application is that Ni-Cu is loaded in the form of microemulsion, the particle size of the microemulsion is larger than the pore size of the small pores of the carrier and smaller than the maximum pore size of the macropores. The Ni-Cu metal salt is contained in the microemulsion, and it is difficult to enter the small pores of the carrier due to steric hindrance, and thus mainly enters the macropores of the carrier. The loading of Pd is carried out by using the solution method, and due to the siphon effect of the small pores, Pd is mainly loaded in the small pores of the catalyst.

[0031] However, since the reduction temperature of Ni-Cu is high, generally 350-400℃, but at this temperature, the aggregation of Pd active centers is more obvious. The present inventors have found by accident that after adding Ce in the carrier, the degree of aggregation of Pd is alleviated; if Pt is further added, the aggregation phenomenon of Pd is also alleviated. The present inventors have also found that if Ce and Pt are loaded at the same time, even after more than 5 times of calcination, the dispersion degree of the active components is still reduced by not more than 20%. The reason may be that the metal salt of Ce forms Ce oxide after calcination, which exists in the form of monolayer distribution. When Pt is co-loaded with Ce, Pt is mainly loaded on the oxide of Ce, and it is speculated that a "atomic wall" of Pt-Ce species may be formed, and the binding force between the two is much higher than that between Pt and alumina. In this way, the atoms of Pt act as an "atomic wall" outside the Pd particles, preventing the growth of Pd particles, thereby playing a role in improving the high-temperature aggregation resistance of Pd active centers. In order to make the "atomic wall" formed by Pt and Ce be able to prevent the growth of Pd particles, Pt and Ce are also loaded by using the solution method, so that they are mainly located in the small pores of the catalyst. 2+ --O 2- --Ce 4+ species, and the binding force between the two is much higher than that between Pt and alumina. In this way, the atoms of Pt act as an "atomic wall" outside the Pd particles, preventing the growth of Pd particles, thereby playing a role in improving the high-temperature aggregation resistance of Pd active centers. In order to make the "atomic wall" formed by Pt and Ce be able to prevent the growth of Pd particles, Pt and Ce are also loaded by using the solution method, so that they are mainly located in the small pores of the catalyst.

[0032] The synergistic effect between W and Pd can improve the selectivity of diene hydrogenation. W is loaded by using the solution method, and the loading of W is after the loading of Pd.

[0033] Therefore, the present application provides a preparation process for the catalyst used in the above-mentioned selective hydrogenation method of the pyrolysis gasoline fraction, in which Pd, Ce, Pt and W are all loaded by using the solution method; Ce and Pt are co-loaded, and the solution method is used to load Ce-Pt and W, which are all after the loading of Pd by using the solution method; Ni-Cu is loaded by using the microemulsion method, and the step of loading Ni-Cu by using the microemulsion method is not limited;

[0034] The preparation process of the microemulsion of Ni-Cu includes the following steps: dissolving the precursor salt of Ni and the precursor salt of Cu in water to obtain an aqueous phase, then mixing the aqueous phase with an oil phase, a surfactant and a co-surfactant, and the mass ratio of the aqueous phase to the oil phase is 2-3, the mass ratio of the surfactant to the oil phase is 0.15-0.6, and the mass ratio of the surfactant to the co-surfactant is 1.0-1.2; and the particle size of the microemulsion is controlled to be greater than the pore diameter of the small pores of the carrier and less than the pore diameter of the large pores of the carrier, and then stirring to form the microemulsion of Ni-Cu with a particle size of greater than 60 nm and less than 500 nm.

[0035] Optionally, in the preparation process of the catalyst, the solution method is used to load Pd, and then Ce-Pt and W are loaded in sequence; or the solution method is used to load Pd, and then W and Ce-Pt are loaded in sequence.

[0036] Optionally, in the preparation process of the catalyst, the microemulsion method is used to load Ni-Cu before the solution method is used to load Pd.

[0037] Optionally, in the step of loading Ni-Cu in the preparation process of the catalyst, the types of the oil phase, the surfactant and the co-surfactant are not particularly limited, and the types of the oil phase, the surfactant and the co-surfactant can be determined according to the precursor salt and the pore structure of the carrier.

[0038] Specifically, the oil phase is C6-C8 saturated alkane or cycloalkane, preferably cyclohexane or n-hexane; the surfactant is ionic surfactant and / or non-ionic surfactant, preferably non-ionic surfactant, more preferably polyethylene glycol octylphenyl ether (Triton X-100) or cetyltrimethylammonium bromide (CTAB); and the co-surfactant is organic alcohol, preferably C4-C6 alcohol, more preferably n-butanol and / or n-pentanol.

[0039] To prevent Ni from entering the small pores and covering the loaded Pd, it is preferred that the solution method is used to load Pd after the microemulsion method is used to load Ni-Cu. Preferably, the preparation method of the catalyst includes the following steps:

[0040] Loading Ni-Cu: after the carrier is immersed in the microemulsion of Ni-Cu, the residual liquid is filtered out, and then dried and calcined to obtain a first semi-finished catalyst;

[0041] Loading Pd: the precursor salt of Pd is dissolved in water, the pH is adjusted to 2.0-2.5 by sodium carbonate, then the first semi-finished catalyst is added for immersion adsorption, and then dried and calcined to obtain a second semi-finished catalyst;

[0042] loading Ce-Pt: dissolving the precursor salt of Ce and the precursor compound of Pt in deionized water to obtain a solution containing Ce and Pt, adjusting pH to 2-2.5 with sodium carbonate, then adding the second semi-finished catalyst for saturated impregnation, drying, and calcining to obtain the third semi-finished catalyst;

[0043] loading W: dissolving the precursor salt of W in deionized water to obtain a solution containing W, then adding the third semi-finished catalyst for saturated impregnation, drying, and calcining to obtain the cracking gasoline fraction selective hydrogenation catalyst.

[0044] Preferably, the preparation method of the catalyst recommended by the present application specifically comprises the following steps:

[0045] loading Ni-Cu: after impregnation of the carrier in the microemulsion of Ni-Cu, filtering out the residual liquid, drying, and calcining to obtain the first semi-finished catalyst;

[0046] loading Pd: dissolving the precursor salt of Pd in water, adjusting pH to 2.0-2.5 with sodium carbonate, then adding the first semi-finished catalyst for impregnation adsorption, drying, and calcining to obtain the second semi-finished catalyst;

[0047] loading W: dissolving the precursor salt of W in deionized water to obtain a solution containing W, then adding the second semi-finished catalyst for saturated impregnation, drying, and calcining to obtain the third semi-finished catalyst;

[0048] loading Ce-Pt: dissolving the precursor salt of Ce and the precursor compound of Pt in deionized water to obtain a solution containing Ce and Pt, adjusting pH to 2-2.5, then adding the third semi-finished catalyst for saturated impregnation, drying, and calcining to obtain the cracking gasoline fraction selective hydrogenation catalyst.

[0049] Alternatively, the catalyst can also be prepared by the following method comprising the following steps:

[0050] loading Pd: dissolving the precursor salt of Pd in water, adjusting pH to 2.0-2.5, then adding the carrier for impregnation adsorption, drying, and calcining to obtain the first semi-finished catalyst;

[0051] loading Ce-Pt: dissolving the precursor salt of Ce and the precursor compound of Pt in deionized water to obtain a solution containing Ce and Pt, adjusting pH to 2-2.5, then adding the first semi-finished catalyst for saturated impregnation, drying, and calcining to obtain the second semi-finished catalyst;

[0052] loading Ni-Cu: after impregnation of the second semi-finished catalyst in the microemulsion of Ni-Cu, filtering out the residual liquid, drying, and calcining to obtain the third semi-finished catalyst;

[0053] Loading W: dissolving the precursor salt of W in deionized water to obtain a W-containing solution, then adding the third semi-finished catalyst to perform saturated impregnation, drying, and calcination to obtain the said pyrolysis gasoline fraction selective hydrogenation catalyst

[0054] Optionally, in the preparation method of the said catalyst, the impregnation time and calcination parameters in each loading step are not specifically limited and can be conventional in the industry. In the recommended preparation method of the said catalyst, in the step of loading Ni-Cu, the impregnation time is 0.5-4 h, the calcination temperature is 300-600℃, and the calcination time is 3-6 h.

[0055] In the step of loading Pd, the impregnation time is 0.5-4 h, the calcination temperature is 400-550℃, and the calcination time is 3-6 h.

[0056] In the step of loading Ce-Pt, the impregnation time is 0.5-4 h, the calcination temperature is 500-600℃, and the calcination time is 3-6 h.

[0057] In the step of loading W, the impregnation and adsorption time is 0.5-4 h, the calcination temperature is 400-550℃, and the calcination time is 3-6 h.

[0058] Optionally, in the preparation method of the said catalyst, the precursor salts of Pd, Ce, Ni, Cu, and W are soluble salts, which can be nitrate salts, chloride salts, or other soluble salts. For example, the precursor salt of Pd can be selected from any one of soluble palladium salts such as palladium chloride and palladium nitrate; the precursor salt of Ni can be selected from any one of soluble nickel salts such as nickel acetate and nickel nitrate; the precursor salt of Cu can be selected from any one of soluble copper salts such as copper nitrate and copper chloride; the precursor salt of W can be selected from any one of soluble tungsten salts such as ammonium metatungstate and ammonium tungstate; and the precursor salt of Ce can be selected from any one of soluble cerium salts such as cerium nitrate. The precursor compound of Pt can be selected from any one of soluble inorganic platinum compounds such as chloroplatinic acid and platinum trichloride.

[0059] Optionally, the reduction temperature of the said catalyst before being put into hydrogenation reaction is 350-400℃.

[0060] The catalyst used in the selective hydrogenation method of the pyrolysis gasoline fraction has the following characteristics: at the beginning of the hydrogenation reaction, the high hydrogenation activity of palladium and the main distribution in small pores result in the selective hydrogenation reaction of dienes mainly occurring in the small pores. With the extension of the running time of the catalyst, a part of the by-products with large molecular weight are generated on the surface of the catalyst. These substances with large molecular size enter the large pores more and stay for a long time, and under the action of nickel, the double bond hydrogenation reaction occurs to generate saturated hydrocarbons or aromatic hydrocarbons without isolated double bonds, and it is not easy to generate substances with larger molecular weight. After regeneration of the catalyst, the reduction is still at 350-400 ℃, and the activity and selectivity of the catalyst do not change obviously after about 5 times of regeneration.

[0061] The hydrogenation method of the present application is suitable for the selective hydrogenation of the pyrolysis gasoline fraction, and has the advantages of high diene hydrogenation activity, coking resistance, hydrogenation stability, strong regeneration performance, and wide operating condition range compared with the prior art. When the hydrogenation method of the present application is used, the catalyst is prepared by using an alumina carrier with bimodal pore distribution and contains at least Pd, Pt, Ce, W, Ni and Cu components, and has good selective hydrogenation performance for pyrolysis gasoline. Especially when the hydrogenation raw material contains trace amounts of water and gum impurities, the catalyst still has good hydrogenation activity and stability.

[0062] The present application has the following beneficial effects:

[0063] 1. The selective hydrogenation method of the pyrolysis gasoline fraction provided by the present application uses a catalyst with excellent hydrogenation activity, selectivity, coking resistance and regeneration performance. The carrier in the catalyst system has a bimodal pore distribution structure, and Pd and W are loaded by a solution method. The siphon effect of the small pores makes Pd and W mainly loaded in the small pores of the catalyst, and the selective hydrogenation reaction of dienes in the hydrogenation raw material occurs in the main active center composed of Pd and W. The synergistic effect between Pd and W can improve the hydrogenation activity and selectivity of dienes. Ni-Cu is loaded in the form of a microemulsion, and the particle size of the microemulsion is between the pore size of the small pores of the carrier and the maximum pore size of the large pores. The space resistance makes it difficult for the microemulsion to enter the small pores of the carrier, so that Ni-Cu is mainly loaded in the large pores of the carrier. Ni-Cu has a saturation hydrogenation function, and the generated gum and other macromolecules in the reaction easily enter the large pores of the catalyst to occur saturation hydrogenation reaction and are carried out of the reactor by the material, thereby facilitating the reduction of coking on the surface of the catalyst. The "atomic fence" formed by Pt and Ce loaded in the small pore structure plays a role in isolating and dispersing Pd particles, which can prevent the growth of Pd particles, improve the dispersion of the active center Pd, and resist high-temperature agglomeration.

[0064] 2、The catalyst used in the selective hydrogenation method of the pyrolysis gasoline fraction provided by the application still has a reduction temperature of 350-400 DEG C after regeneration, and the activity and selectivity of the catalyst after regeneration do not change obviously; after about 5 times of regeneration, the activity and selectivity of the catalyst do not change obviously, and the catalyst still has excellent hydrogenation activity and coking resistance. In addition, the catalyst has good metal dispersion performance, good saturation hydrogenation performance of large molecular compounds such as gum, and the active metal is not easy to agglomerate during high-temperature use and regeneration, so that the catalyst has good olefin hydrogenation activity, coking resistance and regeneration performance.

[0065] 3、The selective hydrogenation method of the pyrolysis gasoline fraction provided by the application uses a fixed bed reactor which has simple structure, wide application, mature technology, convenient catalyst loading, start-up and regeneration operation, and small investment; by using the fixed bed reactor and the catalyst provided by the application, the diene hydrogenation activity and coking resistance of the catalyst can be greatly improved, the service life of the catalyst can be prolonged, and the long-term stable operation of the hydrogenation process can be ensured. DETAILED DESCRIPTION

[0066] The application will be specifically described below by examples. It is necessary to point out here that the following examples are only used for further illustrating the application, and cannot be understood as limiting the protection scope of the application, and those skilled in the art can make some non-essential improvements and adjustments to the application according to the above content of the application.

[0067] The specific experimental steps or conditions are not specified in the examples, and can be performed according to the conventional experimental steps described in the literature in the art. The reagents or instruments used are not specified by the manufacturer, and are all conventional reagent products that can be obtained by market purchase.

[0068] Evaluation method:

[0069] The microemulsion particle size distribution of Ni-Cu is tested by using a dynamic light scattering particle size analyzer.

[0070] The content of each component in the catalyst is analyzed and detected by using the national standards "General Rules for Atomic Absorption Spectrometry" GB / T15337 and "General Rules for Flame Atomic Absorption Spectrometry of Chemical Reagents" GB19723;

[0071] The specific surface area and pore size of the carrier are determined according to the GB / T 21650 standard;

[0072] The metal dispersion is determined by using hydrogen-oxygen titration method in a Micromeritics Autochem2920 chemical adsorption instrument.

[0073] The diene value of the oil product is determined by using the UOP 326-2008 method;

[0074] Bromine value of oil: measured according to SH / T 0236-92 standard;

[0075] Water content of oil: measured according to GB / T 11133-89 standard;

[0076] Sulfur content of oil: measured by WK-2B micro-coulomb instrument;

[0077] Carbon content on catalyst surface: elemental analyzer.

[0078] The application is further illustrated below by specific examples, but the application is not considered to be limited to this.

[0079] Example 1

[0080] Catalyst carrier: commercially available bimodal pore distribution clover-shaped strip-shaped alumina-titania carrier, mass content of titania is 5wt%, after calcination at 1000℃, bimodal pore diameter distribution range is 10-40nm and 200-500nm, specific surface area is 110m 2 / g. 100g of the carrier is weighed.

[0081] Preparation of CAT1 catalyst:

[0082] (1) Nickel nitrate and copper nitrate are weighed and dissolved in 70g of deionized water, 35g of cyclohexane is added, 15g of CTAB is added, 13g of n-pentanol is added, and the mixture is fully stirred to form a microemulsion. 100g of the high-temperature calcined carrier is immersed in the prepared microemulsion, shaken for 240min, the remaining liquid is filtered out, dried at 100℃ for 4h, and calcined at 600℃ for 3h to obtain semi-finished catalyst A1;

[0083] (2) Pd active component impregnation solution is prepared by weighing palladium nitrate, and the pH is adjusted to 2.1 with sodium carbonate. The semi-finished catalyst A1 is immersed in the prepared Pd active component solution, and after 30min of immersion, it is dried at 120℃ for 3h and calcined at 550℃ for 3h to obtain semi-finished catalyst B1;

[0084] (3) Ammonium metatungstate is dissolved in deionized water, and the semi-finished catalyst B1 is immersed in the prepared solution. After 100min of immersion, it is dried at 100℃ for 4h and calcined at 450℃ for 4h to obtain semi-finished catalyst C1;

[0085] (4) Active component impregnation solution is prepared by weighing chloroplatinic acid and cerium nitrate, and the pH is adjusted to 2.4 with sodium carbonate. The semi-finished catalyst C1 is immersed in the prepared solution, and after 30min of immersion, it is dried at 120℃ for 3h and calcined at 550℃ for 4.5h to obtain catalyst CAT1.

[0086] The particle size of the prepared microemulsion was 90 nm as determined by dynamic light scattering method.

[0087] Reduction of the catalyst:

[0088] Before use, it was placed in a fixed bed reaction device and reduced at a temperature of 380°C for 10 h in a hydrogen atmosphere.

[0089] Example 2

[0090] Catalyst carrier: a commercially available bimodal pore distribution cylindrical alumina carrier was used, which was calcined at 1030°C, had a bimodal pore size distribution ranging from 10 to 60 nm and 200 to 500 nm, and a specific surface area of 73 m 2 / g. 100 g of the carrier was weighed.

[0091] Preparation of CAT2 catalyst:

[0092] (1) Nickel acetate and copper chloride were weighed and dissolved in 65 g of deionized water, 22 g of cyclohexane was added, 11 g of Triton X-100 was added, and 11 g of n-hexanol was added, and the mixture was stirred to form a microemulsion. 100 g of the high-temperature calcined carrier was immersed in the prepared microemulsion, shaken for 30 min, the remaining liquid was filtered out, dried at 100°C for 4 h, and calcined at 300°C for 6 h to obtain semi-finished catalyst A2;

[0093] (2) PdCl2 was weighed and prepared into an active component impregnation solution, and the pH was adjusted to 2.2 with Na2CO3. The prepared semi-finished catalyst A2 was immersed in the prepared Pd active component solution, and after 100 min of immersion, it was dried at 100°C for 5 h and calcined at 450°C for 4 h to obtain semi-finished catalyst B2;

[0094] (3) Ce(NO3)3 and H2PtCl6 were weighed and prepared into an active component impregnation solution, and the pH was adjusted to 2.3 with Na2CO3. The semi-finished catalyst B2 was added to the prepared solution, and after 150 min of immersion, it was dried at 100°C and calcined at 500°C for 6 h to obtain semi-finished catalyst C2;

[0095] (4) Ammonium metatungstate was weighed and dissolved in deionized water, and the semi-finished catalyst C2 was immersed in the prepared solution. After 180 min of immersion, it was dried at 100°C for 4 h and calcined at 520°C for 6 h to obtain catalyst CAT2.

[0096] The particle size of the prepared microemulsion was 150 nm as determined by dynamic light scattering method.

[0097] Reduction of the catalyst:

[0098] Before use, it was placed in a fixed bed reaction device and reduced at a temperature of 350°C for 9 h in a hydrogen atmosphere.

[0099] Example 3

[0100] Catalyst carrier: A commercially available bimodal pore distribution spherical alumina carrier was used, which was calcined at 1020°C, had a bimodal pore size distribution ranging from 15-60 nm and 150-400 nm, and a specific surface area of 120 m 2 / g. 100 g of the carrier was weighed.

[0101] Preparation of CAT3 catalyst:

[0102] (1) Nickel nitrate, copper nitrate were weighed and dissolved in 70 g of deionized water, 28 g of cyclohexane, 5 g of Triton X-100, and 5 g of n-butanol were added, and the mixture was stirred to form a microemulsion. 100 g of the high-temperature calcined carrier was immersed in the prepared microemulsion, shaken for 60 min, the residual liquid was filtered out, dried at 80°C for 5 h, and calcined at 400°C for 5 h to obtain semi-finished catalyst A3;

[0103] (2) Palladium nitrate was weighed and prepared into an active component impregnation solution, and the pH was adjusted to 2.4 with sodium carbonate. The semi-finished catalyst A3 was immersed in the prepared Pd active component solution, and after 150 min of immersion, it was dried at 100°C for 5 h and calcined at 500°C for 4 h to obtain semi-finished catalyst B3;

[0104] (3) Cerium nitrate and chloroplatinic acid were weighed and prepared into an active component impregnation solution, and the pH was adjusted to 2.2. The semi-finished catalyst B3 was added to the prepared solution, and after 240 min of immersion, it was dried at 100°C for 4 h and calcined at 580°C for 6 h to obtain semi-finished catalyst C3;

[0105] (4) Ammonium tungstate was dissolved in deionized water, and the semi-finished catalyst C3 was immersed in the prepared solution. After 240 min of immersion, it was dried at 140°C for 2 h and calcined at 550°C for 3 h to obtain the catalyst CAT3.

[0106] The particle size of the prepared microemulsion emulsion was 130 nm as determined by dynamic light scattering.

[0107] Reduction of the catalyst:

[0108] Before use, it was placed in a fixed bed reaction device and reduced at a hydrogen atmosphere and a temperature of 360°C for 10 h.

[0109] Example 4

[0110] Catalyst carrier: A commercially available bimodal pore distribution clover-shaped alumina carrier was used, which was calcined at 1010°C, had a bimodal pore size distribution ranging from 10-60 nm and 150-500 nm, and a specific surface area of 90 m 2 / g. 100 g of the carrier was weighed.

[0111] Preparation of CAT4 catalyst:

[0112] (1) Weigh nickel nitrate, copper nitrate into 75 g of deionized water, add cyclohexane 30 g, add Triton X-100 4.5 g, add n-butanol 4.0 g, and fully stir to form a microemulsion. Dip 100 g of the high-temperature calcined carrier prepared above into the prepared microemulsion, shake for 100 min, filter out the remaining liquid, dry at 100°C for 4 h, and calcine at 500°C for 4 h to obtain semi-finished catalyst A4.

[0113] (2) Weigh palladium chloride to prepare an active component impregnation solution, adjust the pH to 2.3 with sodium carbonate, and dip the prepared semi-finished catalyst A4 into the prepared Pd active component solution. After impregnation for 60 min, dry at 100°C for 5 h, and calcine at 430°C for 5 h to obtain semi-finished catalyst B4.

[0114] (3) Weigh cerium nitrate and chloroplatinic acid to prepare an active component impregnation solution, adjust the pH to 2.1 with sodium carbonate, and dip the semi-finished catalyst B4 into the prepared solution. After impregnation for 100 min, dry at 100°C for 5 h, and calcine at 600°C for 3 h to obtain semi-finished catalyst C4.

[0115] (4) Weigh ammonium tungstate into deionized water, and dip the semi-finished catalyst C4 into the prepared solution. After impregnation for 60 min, dry at 100°C for 4 h, and calcine at 400°C for 6 h to obtain catalyst CAT4.

[0116] The particle size of the prepared microemulsion is 140 nm as determined by dynamic light scattering.

[0117] Reduction of the catalyst:

[0118] Before use, place in a fixed bed reaction device, reduce at a hydrogen atmosphere and a temperature of 370°C for 8 h.

[0119] Example 5

[0120] Catalyst carrier: commercially available bimodal pore distribution clover-shaped alumina carrier, calcined at 960°C, bimodal pore size distribution range of 10-50 nm and 100-450 nm, specific surface area of 105 m 2 / g. Weigh 100 g of the carrier.

[0121] Preparation of CAT5 catalyst:

[0122] (1) Weigh palladium chloride to prepare an active component impregnation solution, adjust the pH to 2.0 with sodium carbonate, and dip 100 g of the high-temperature calcined carrier prepared above into the prepared Pd salt solution. After impregnation for 180 min, dry at 120°C for 3 h, and calcine at 450°C for 4 h to obtain semi-finished catalyst A5.

[0123] (2) Take the platinum trichloride, cerium nitrate to prepare the active component impregnation solution, adjust the pH to 2.5 with sodium carbonate, and then immerse the semi-finished catalyst A5 into the prepared solution. After 90 min of immersion, dry at 120°C for 3h, and calcine at 550°C for 5h to obtain the semi-finished catalyst B5;

[0124] (3) Take the nickel nitrate and copper nitrate, and dissolve them in 80g of deionized water. Add 35g of n-hexane, 21g of Triton X-100, and 20g of n-hexanol, and fully stir to form a microemulsion. Then immerse the semi-finished catalyst B5 into the prepared microemulsion, shake for 200 min, filter out the remaining liquid, dry at 100°C for 4h, and calcine at 450°C for 5h to obtain the semi-finished catalyst C5;

[0125] (4) Take the ammonium metatungstate and dissolve it in deionized water. Dissolve the semi-finished catalyst C5 in the prepared ammonium metatungstate solution, immerse for 30 min, dry at 100°C for 4h, and calcine at 480°C for 5h to obtain the catalyst CAT5.

[0126] The particle size of the prepared microemulsion is 120 nm by dynamic light scattering method.

[0127] Reduction of the catalyst:

[0128] Before use, place it in a fixed bed reaction device, reduce it at a temperature of 390°C for 8h in a hydrogen atmosphere.

[0129] Example 6

[0130] Catalyst carrier: A commercially available bimodal pore distribution spherical alumina carrier is used, which is calcined at 950°C, has a bimodal pore size distribution ranging from 10-30nm and 100-300nm, and has a specific surface area of 140m 2 / g. Take 100g of the carrier.

[0131] Preparation of the CAT6 catalyst:

[0132] (1) Take the nickel acetate and copper nitrate, and dissolve them in 60g of deionized water. Add 22g of cyclohexane, 9.0g of CTAB, and 9.0g of n-pentanol, and fully stir to form a microemulsion. Then immerse the 100g of high-temperature calcined carrier into the prepared microemulsion, shake for 150 min, filter out the remaining liquid, dry at 100°C for 4h, and calcine at 550°C for 4h to obtain the semi-finished catalyst A6;

[0133] (2) Take the palladium chloride and prepare the active component impregnation solution, adjust the pH to 2.5 with sodium carbonate, and then immerse the semi-finished catalyst A6 into the prepared Pd active component solution. After 240 min of immersion, dry at 120°C for 3h, and calcine at 400°C for 6h to obtain the semi-finished catalyst B6;

[0134] (3) Take chloroplatinic acid, cerium nitrate to prepare active component impregnation solution, adjust pH to 2.0 with sodium carbonate, immerse semi-finished catalyst B6 into the prepared solution, after impregnation for 200 min, dry at 120°C for 3h, calcine at 520°C for 5h, to obtain semi-finished catalyst C6;

[0135] (4) Take ammonium metatungstate and dissolve in deionized water, immerse semi-finished catalyst C6 into the prepared solution, after impregnation for 150 min, dry at 100°C for 4h, calcine at 450°C for 4h, to obtain catalyst CAT6.

[0136] The particle size of the prepared microemulsion is 100 nm by dynamic light scattering method.

[0137] Reduction of the catalyst:

[0138] Before use, place in a fixed bed reaction device, reduce at 400°C under hydrogen atmosphere for 8h.

[0139] Comparative Example 1

[0140] This comparative example uses the catalyst carrier in Example 1, and the catalyst is prepared by a method similar to Example 1, the only difference being that no Ce is loaded in this comparative example. The preparation process of D1 catalyst is as follows:

[0141] (1) Take nickel nitrate, copper nitrate and dissolve in 70g deionized water, add cyclohexane 35g, add CTAB 15g, add n-pentanol 13g, fully stir to form a microemulsion, immerse the weighed 100g high-temperature calcined carrier into the prepared microemulsion, shake for 240 min, filter out the residual liquid, dry at 100°C for 4h, calcine at 600°C for 3h, to obtain semi-finished catalyst A1;

[0142] (2) Take palladium nitrate and prepare active component impregnation solution, adjust pH to 2.1 with sodium carbonate, immerse semi-finished catalyst A1 into the prepared Pd active component solution, after impregnation for 30 min, dry at 120°C for 3h, calcine at 550°C for 3h, to obtain semi-finished catalyst B1;

[0143] (3) Take ammonium metatungstate and dissolve in deionized water, immerse semi-finished catalyst B1 into the prepared solution, after impregnation for 100 min, dry at 100°C for 4h, calcine at 450°C for 4h, to obtain semi-finished catalyst C1;

[0144] (4) Take chloroplatinic acid and prepare active component impregnation solution, adjust pH to 2.4 with sodium carbonate, immerse semi-finished catalyst C1 into the prepared solution, after impregnation for 30 min, dry at 120°C for 3h, calcine at 550°C for 4.5h, to obtain catalyst D1.

[0145] The particle size of the prepared microemulsion was 90 nm as determined by dynamic light scattering method.

[0146] Reduction of the catalyst:

[0147] Before use, it was placed in a fixed bed reaction device and reduced at a temperature of 380°C for 10 h in a hydrogen atmosphere.

[0148] Comparative Example 2

[0149] This comparative example used the catalyst carrier in Example 1, and the catalyst was prepared in a similar manner as in Example 1, except that no Pt was loaded in this comparative example. The preparation process of the D2 catalyst was as follows:

[0150] (1) Nickel nitrate and copper nitrate were weighed and dissolved in 70 g of deionized water, 35 g of cyclohexane was added, 15 g of CTAB was added, 13 g of n-pentanol was added, and the mixture was stirred thoroughly to form a microemulsion. 100 g of the high-temperature calcined carrier was immersed in the prepared microemulsion and shaken for 240 min. The remaining liquid was filtered out, and the catalyst was dried at 100°C for 4 h and calcined at 600°C for 3 h to obtain a semi-finished catalyst A1;

[0151] (2) Pd active component impregnation solution was prepared by weighing palladium nitrate, and the pH was adjusted to 2.1 with sodium carbonate. The semi-finished catalyst A1 was immersed in the prepared Pd active component solution, and after 30 min of immersion, it was dried at 120°C for 3 h and calcined at 550°C for 3 h to obtain a semi-finished catalyst B1;

[0152] (3) Ammonium metatungstate was dissolved in deionized water, and the semi-finished catalyst B1 was immersed in the prepared solution. After 100 min of immersion, it was dried at 100°C for 4 h and calcined at 450°C for 4 h to obtain a semi-finished catalyst C1;

[0153] (4) Cerium nitrate was prepared into an active component impregnation solution, and the pH was adjusted to 2.4 with sodium carbonate. The semi-finished catalyst C1 was immersed in the prepared solution, and after 30 min of immersion, it was dried at 120°C for 3 h and calcined at 550°C for 4.5 h to obtain the catalyst D2.

[0154] The particle size of the prepared microemulsion was 90 nm as determined by dynamic light scattering method.

[0155] Reduction of the catalyst:

[0156] Before use, it was placed in a fixed bed reaction device and reduced at a temperature of 380°C for 10 h in a hydrogen atmosphere.

[0157] Comparative Example 3

[0158] The comparative example adopts the catalyst carrier in Example 2, and the preparation method of the catalyst is similar to that in Example 2, and the difference is only that Ce and Pt are loaded respectively in the comparative example. The preparation process of the specific D3 catalyst is as follows:

[0159] (1) The nickel acetate and copper chloride were weighed and dissolved in 65 g of deionized water, 22 g of cyclohexane was added, 11 g of Triton X-100 was added, and 11 g of n-hexanol was added, and the mixture was stirred to form a microemulsion. 100 g of the high-temperature calcined carrier was immersed in the prepared microemulsion, shaken for 30 min, the residual liquid was filtered out, dried at 100°C for 4 h, and calcined at 300°C for 6 h to obtain a semi-finished catalyst A2;

[0160] (2) The palladium chloride was weighed and prepared into an active component impregnation solution, and the pH was adjusted to 2.2 with sodium carbonate. The prepared semi-finished catalyst A2 was immersed in the prepared Pd active component solution, and after impregnation for 100 min, it was dried at 100°C for 5 h and calcined at 450°C for 4 h to obtain a semi-finished catalyst B2;

[0161] (3) The chloroplatinic acid was weighed and prepared into an active component impregnation solution, and the pH was adjusted to 2.3 with sodium carbonate. The semi-finished catalyst B2 was added to the prepared solution, and after impregnation for 150 min, it was dried at 100°C and calcined at 500°C for 6 h to obtain a semi-finished catalyst C2-1;

[0162] (4) The cerium nitrate was weighed and prepared into an active component impregnation solution, and the pH was adjusted to 2.3 with sodium carbonate. The semi-finished catalyst C2-1 was added to the prepared solution, and after impregnation for 150 min, it was dried at 100°C and calcined at 500°C for 6 h to obtain a semi-finished catalyst C2-2;

[0163] (5) The ammonium metatungstate was weighed and dissolved in deionized water, and the semi-finished catalyst C2-2 was immersed in the prepared solution. After impregnation for 180 min, it was dried at 100°C for 4 h and calcined at 520°C for 6 h to obtain a catalyst D3.

[0164] The particle size of the prepared microemulsion was measured by dynamic light scattering method, and the particle size was 150 nm.

[0165] Reduction of the catalyst:

[0166] Before use, it was placed in a fixed bed reaction device and reduced at a hydrogen atmosphere and a temperature of 350°C for 9 h.

[0167] Comparative Example 4

[0168] The comparative example adopts the catalyst carrier in Example 2, and the preparation method of the catalyst is similar to that in Example 2, and the difference is only that the loading order of the active components is different. The preparation process of the specific D4 catalyst is as follows:

[0169] (1) Weigh nickel acetate, copper chloride into 65 g of deionized water, add 22 g of cyclohexane, 11 g of Triton X-100, and 11 g of n-hexanol, and stir thoroughly to form a microemulsion. Dip 100 g of high-temperature calcined carrier into the prepared microemulsion, shake for 30 min, filter out the remaining liquid, dry at 100°C for 4 h, and calcine at 300°C for 6 h to obtain semi-finished catalyst A2;

[0170] (2) Weigh cerium nitrate and chloroplatinic acid to prepare an active component impregnation solution, adjust the pH to 2.3 with sodium carbonate, and then dip the semi-finished catalyst A2 into the prepared solution. After impregnation for 150 min, dry at 100°C and calcine at 500°C for 6 h to obtain semi-finished catalyst B2.

[0171] (3) Weigh palladium chloride to prepare an active component impregnation solution, adjust the pH to 2.2 with sodium carbonate, and then dip the prepared semi-finished catalyst B2 into the prepared Pd active component solution. After impregnation for 100 min, dry at 100°C for 5 h and calcine at 450°C for 4 h to obtain semi-finished catalyst C2.

[0172] (4) Weigh ammonium metatungstate into deionized water, and then dip the semi-finished catalyst C2 into the prepared solution. After impregnation for 180 min, dry at 100°C for 4 h and calcine at 520°C for 6 h to obtain catalyst D4.

[0173] The particle size of the prepared microemulsion is 150 nm as determined by dynamic light scattering.

[0174] Reduction of the catalyst:

[0175] Before use, place it in a fixed bed reaction device and reduce it at a hydrogen atmosphere and a temperature of 350°C for 9 h.

[0176] Comparative Example 5

[0177] This comparative example uses the catalyst carrier in Example 3, and the preparation method of catalyst D5 is similar to that of Example 3, except that the amounts of cerium nitrate and chloroplatinic acid are different, resulting in different contents of Pt and Ce in the final catalyst.

[0178] Comparative Example 6

[0179] This comparative example uses the catalyst carrier in Example 4, and the preparation method of the catalyst is similar to that of Example 4, except that in this comparative example, Ni and Cu are loaded using the solution method. The specific preparation process of catalyst D6 is as follows:

[0180] (1) Take nickel nitrate, copper nitrate and dissolve in deionized water to prepare an impregnation solution, take 100 g of high-temperature calcined carrier and immerse it in the prepared solution for saturation impregnation, after 100 min of impregnation, dry at 100°C for 4h, calcine at 500°C for 4h, to obtain semi-finished catalyst A4;

[0181] (2) Take PdCl2 and prepare an active component impregnation solution, adjust the pH to 2.3 with Na2CO3, immerse the prepared semi-finished catalyst A4 into the prepared Pd active component solution, after 60 min of impregnation, dry at 100°C for 5h, calcine at 430°C for 5h, to obtain semi-finished catalyst B4;

[0182] (3) Take Ce(NO3)3 and H2PtCl6 and prepare an active component impregnation solution, adjust the pH to 2.1 with Na2CO3, immerse the semi-finished catalyst B4 into the prepared solution, after 100 min of impregnation, dry at 100°C for 5h, calcine at 600°C for 3h, to obtain semi-finished catalyst C4;

[0183] (4) Take NH4WO3 and dissolve in deionized water, immerse the semi-finished catalyst C4 into the prepared solution, after 60 min of impregnation, dry at 100°C for 4h, calcine at 400°C for 6h, to obtain catalyst D6.

[0184] Comparative Example 7

[0185] The preparation method of catalyst D7 in this comparative example is similar to that of Example 5, the only difference being that the carrier used is different, and in this comparative example, the catalyst carrier is a unimodal pore structure, which is as follows:

[0186] Catalyst carrier: commercially available bimodal pore distribution clover-shaped alumina carrier, calcined at 1000°C, pore size distribution range of 5-100 nm, specific surface area of 80 m 2 / g.

[0187] Comparative Example 8

[0188] The preparation method of catalyst D8 in this comparative example is similar to that of Example 5, the only difference being that the pore size distribution of the carrier used is different, and in this comparative example, the catalyst carrier is as follows:

[0189] Catalyst carrier: commercially available bimodal pore distribution clover-shaped alumina carrier, calcined at 940°C, bimodal pore size distribution range of 2-30 nm and 100-300 nm, specific surface area of 145 m 2 / g.

[0190] Comparative Example 9

[0191] The catalyst carrier in Example 6 was used in the present comparative example, and the catalyst was prepared in a similar manner to Example 6, except that the amount of surfactant used in the Ni-Cu microemulsion was different. In the preparation process, the surfactant / oil phase in Example 6 was replaced with 0.8. The specific preparation steps of the catalyst in the present comparative example are as follows:

[0192] (1) Nickel acetate and copper nitrate were weighed and dissolved in 60 g of deionized water, 22 g of cyclohexane was added, 17.5 g of CTAB was added, and 17.5 g of n-pentanol was added. The mixture was stirred to form a microemulsion. 100 g of the high-temperature calcined carrier was immersed in the prepared microemulsion and shaken for 150 min. The remaining liquid was filtered out, and the catalyst was dried at 100°C for 4 h and calcined at 550°C for 4 h to obtain semi-finished catalyst A6.

[0193] (2) PdCl2 was weighed and prepared into an active component impregnation solution. The pH was adjusted to 2.5 with Na2CO3. The semi-finished catalyst A6 was immersed in the prepared Pd active component solution, and after 240 min of immersion, it was dried at 120°C for 3 h and calcined at 400°C for 6 h to obtain semi-finished catalyst B6.

[0194] (3) H2PtCl6 and Ce(NO3)4 were weighed and prepared into an active component impregnation solution. The pH was adjusted to 2.0 with Na2CO3. The semi-finished catalyst B6 was immersed in the prepared solution, and after 200 min of immersion, it was dried at 120°C for 3 h and calcined at 520°C for 5 h to obtain semi-finished catalyst C6.

[0195] (4) Ammonium metatungstate was weighed and dissolved in deionized water. The semi-finished catalyst C6 was immersed in the prepared solution, and after 150 min of immersion, it was dried at 100°C for 4 h and calcined at 450°C for 4 h to obtain catalyst D9.

[0196] The particle size of the prepared microemulsion was measured by dynamic light scattering method and was 58 nm.

[0197] The catalysts prepared in the above examples and comparative examples were tested for component content, and the specific results are shown in Table 1.

[0198] Table 1

[0199]

[0200] The catalysts prepared in the above examples were tested for metal dispersion, and the specific results are shown in Table 2.

[0201] Table 2

[0202]

[0203] Example 7

[0204] The present example provides a selective hydrogenation method of pyrolysis gasoline fraction, using C6-C7 pyrolysis gasoline fraction as raw material (properties shown in Table 3), using CAT1 catalyst in an adiabatic fixed bed reactor for evaluation, and the catalyst loading is 100 mL. The specific hydrogenation conditions are as follows:

[0205] The reaction temperature is 45°C, the reaction pressure is 3.0 MPa, the feed volume space velocity of fresh C6-C7 pyrolysis gasoline fraction is 3.0 h -1 , the hydrogen / oil volume ratio is 250:1, the dilution ratio of raw material and product is 1:1, and the evaluation time is 500 h.

[0206] Examples 8-12 and Comparative Examples 10-18

[0207] The selective hydrogenation method of pyrolysis gasoline fraction provided in Examples 8-12 and Comparative Examples 10-18 is similar to Example 7, and the catalyst used in each example and comparative example, the hydrogenation raw material and the hydrogenation reaction parameters are shown in Table 4.

[0208] Table 3 Properties of pyrolysis gasoline fraction raw material

[0209]

[0210] Table 4 Catalyst, hydrogenation raw material and hydrogenation reaction parameters used in Examples 7-12 and Comparative Examples 10-18

[0211]

[0212]

[0213] Note: When the hydrogenation raw material is C6-C7 fraction, the dilution ratio (mass ratio) of raw material and product is 1:1, and when the hydrogenation raw material is C5-C9 fraction, the dilution ratio (mass ratio) of raw material and product is 1:3.

[0214] In the above Examples 7-12 and Comparative Examples 10-18, the hydrogenation evaluation effect after 500 h of operation is shown in Table 5.

[0215] Table 5 Hydrogenation evaluation results of Examples 7-12 and Comparative Examples 10-18

[0216]

[0217] In the above table, the calculation formula of diene hydrogenation selectivity is as follows:

[0218]

[0219] After each catalyst is operated for 500 hours, the catalysts are regenerated by using the air burning method outside the reactor, the regeneration temperature is 500℃, and the catalysts after regenerated once and five times are used for the pyrolysis gasoline hydrogenation, the hydrogenation reaction process conditions are the same as shown in Table 3, and the specific hydrogenation evaluation results are shown in Table 6 and Table 7.

[0220] Table 6: The first regeneration performance of each catalyst

[0221]

[0222] Table 7: The operation results of each catalyst after regenerated five times for 500 hours

[0223]

[0224]

[0225] From the data in the above table, it can be seen that the hydrogenation method of the present application, and the catalyst of the present application, have excellent diene hydrogenation activity, selectivity, anti-coking performance and regeneration performance, and the hydrogenation products meet the requirements of the selective hydrogenation of the pyrolysis gasoline fraction.

[0226] Of course, the present application can have other various embodiments, and those skilled in the art can make various corresponding changes and modifications according to the present application without departing from the spirit and essence of the present application, but these corresponding changes and modifications should all belong to the protection scope of the claims of the present application.

Claims

1. A selective hydrogenation method for a cracked gasoline fraction, comprising the following steps: mixing the cracked gasoline fraction with hydrogen and then feeding it into a fixed-bed reactor for a hydrogenation reaction, characterized in that, The hydrogenation reaction temperature is 30~100℃, the reaction pressure is 2.0~5.0MPa, the feed volume hourly space velocity of the fresh cracked gasoline fraction is 0.5~3.5h-1, and the hydrogen-to-oil volume ratio is 80~300:

1. The catalyst used in the hydrogenation reaction includes a support and an active component. The support includes alumina, and the specific surface area of ​​the alumina is 60–150 m². 2 The catalyst has a bimodal pore structure with a diameter of 10–60 nm and a diameter of 100–500 nm. The active components include Pd, Pt, Ce, W, Ni, and Cu. Based on the mass of the catalyst (100%), the Pd content is 0.2 wt%–0.5 wt%, the Pt content is 0.02 wt%–0.15 wt%, the Ce content is 0.5 wt%–4.0 wt%, the W content is 0.2 wt%–2.5 wt%, the Ni content is 0.5 wt%–5.0 wt%, and the Cu content is 0.5 wt%–3.0 wt%. Ni-Cu is loaded using a microemulsion method, with the microemulsion particle size controlled to distribute Ni and Cu within the macropores of the support. Pd, Pt, Ce, and W are all loaded using a solution method, primarily within the micropores of the support, with Pt and Ce being loaded simultaneously. Solution loading of Ce-Pt follows solution loading of Pd.

2. The selective hydrogenation method for cracked gasoline fractions as described in claim 1, characterized in that, The hydrogenation reaction temperature is 35~70℃, the reaction pressure is 2.4~3.5MPa, and the feed volume hourly space velocity (VHSV) of the fresh cracked gasoline fraction is 1.0~3.0 h⁻¹. -1 The hydrogen-to-oil volume ratio is 80-200:

1.

3. The selective hydrogenation method for cracked gasoline fractions as described in claim 1, characterized in that, The fixed-bed reactor is an adiabatic reactor or an isothermal reactor.

4. The selective hydrogenation method for cracked gasoline fractions as described in claim 1, characterized in that, In the preparation process of the catalyst, Pd, Ce, Pt and W are all loaded by solution method, Ce and Pt are loaded simultaneously, and the solution loading of Ce-Pt and W are both after the solution loading of Pd. The preparation process of Ni-Cu microemulsion includes the following steps: dissolving Ni precursor salt and Cu precursor salt in water to obtain an aqueous phase; then mixing the aqueous phase with an oil phase, a surfactant, and a co-surfactant to form a Ni-Cu microemulsion; wherein the mass ratio of the aqueous phase to the oil phase is 2-3, the mass ratio of the surfactant to the oil phase is 0.15-0.6, and the mass ratio of the surfactant to the co-surfactant is 1.0-1.

2.

5. The selective hydrogenation method for cracked gasoline fractions as described in claim 4, characterized in that, In the preparation of the catalyst, Pd is loaded in solution, followed by Ce-Pt and W in sequence; or Pd is loaded in solution, followed by W and Ce-Pt in sequence.

6. The selective hydrogenation method for cracked gasoline fractions as described in claim 4, characterized in that, In the preparation of the catalyst, Ni-Cu is loaded using the microemulsion method before Pd is loaded using the solution method.

7. The selective hydrogenation method for cracked gasoline fractions as described in claim 4, characterized in that, The oil phase is a C6-C8 saturated alkane or cycloalkane; The surfactant is an ionic surfactant and / or a nonionic surfactant; The co-surfactant is an organic alcohol.

8. The selective hydrogenation method for cracked gasoline fractions as described in claim 4, characterized in that, The preparation of the catalyst includes the following steps: Ni-Cu supported: The support is added to the Ni-Cu microemulsion for impregnation, the residual liquid is filtered off, and the mixture is dried and calcined to obtain the first semi-finished catalyst. Pd loading: Dissolve the Pd precursor salt in water, adjust the pH to 2.0-2.5, then add the first semi-finished catalyst for impregnation and adsorption, and then dry and calcine to obtain the second semi-finished catalyst. Ce-Pt loading: Ce precursor salt and Pt precursor compound are dissolved in deionized water to obtain Ce and Pt solution. The pH is adjusted to 2-2.5, and then the second semi-finished catalyst is added for saturated impregnation, dried and calcined to obtain the third semi-finished catalyst. Loading W: Dissolve the precursor salt of W in deionized water to obtain a W-containing solution, then add the third semi-finished catalyst for saturated impregnation, dry, and calcinate.

9. The selective hydrogenation method for cracked gasoline fractions as described in claim 4, characterized in that, The preparation of the catalyst includes the following steps: Ni-Cu supported: The support is added to the Ni-Cu microemulsion for impregnation, the residual liquid is filtered off, and the mixture is dried and calcined to obtain the first semi-finished catalyst. Pd loading: Dissolve the Pd precursor salt in water, adjust the pH to 2.0-2.5, then add the first semi-finished catalyst for impregnation and adsorption, and then dry and calcine to obtain the second semi-finished catalyst. Loading W: Dissolve the precursor salt of W in deionized water to obtain a W-containing solution, then add the second semi-finished catalyst for saturated impregnation, dry, and calcine to obtain the fourth semi-finished catalyst. Ce-Pt loading: Ce precursor salt and Pt precursor compound are dissolved in deionized water to obtain Ce and Pt solution. The pH is adjusted to 2-2.5, and then the fourth semi-finished catalyst is added for saturated impregnation, drying, and calcination.

10. The selective hydrogenation method for cracked gasoline fractions as described in claim 4, characterized in that, The preparation of the catalyst includes the following steps: Pd loading: The precursor salt of Pd is dissolved in water, the pH is adjusted to 2.0-2.5, and then the carrier is added for impregnation and adsorption. After drying and calcination, the fifth semi-finished catalyst is obtained. Ce-Pt loading: Ce precursor salt and Pt precursor compound are dissolved in deionized water to obtain Ce and Pt solution. The pH is adjusted to 2-2.5, and then the fifth semi-finished catalyst is added for saturated impregnation, dried and calcined to obtain the sixth semi-finished catalyst. Ni-Cu supported catalyst: The sixth semi-finished catalyst is added to the Ni-Cu microemulsion for impregnation, the residual liquid is filtered off, and the catalyst is dried and calcined to obtain the seventh semi-finished catalyst; Loading W: Dissolve the precursor salt of W in deionized water to obtain a W-containing solution, then add the seventh semi-finished catalyst for saturated impregnation, dry, and calcinate.

11. The selective hydrogenation method for cracked gasoline fractions as described in claim 1, characterized in that, The Pd content is 0.25wt% to 0.45wt%.

12. The selective hydrogenation method for cracked gasoline fractions as described in claim 1, characterized in that, The Pt content is 0.05wt%~0.10wt%.

13. The selective hydrogenation method for cracked gasoline fractions as described in claim 1, characterized in that, The Ce content is 1.0wt% to 3.0wt%.

14. The selective hydrogenation method for cracked gasoline fractions as described in claim 1, characterized in that, The W content is 0.6wt% to 2.0wt%.

15. The selective hydrogenation method for cracked gasoline fractions as described in claim 1, characterized in that, The Ni content is 1.5wt% to 3.5wt%.

16. The selective hydrogenation method for cracked gasoline fractions as described in claim 1, characterized in that, The Cu content is 1.0wt% to 2.5wt%.

17. The selective hydrogenation method for cracked gasoline fractions as described in claim 3, characterized in that, The fixed-bed reactor is an adiabatic reactor.

18. The selective hydrogenation method for cracked gasoline fractions as described in claim 7, characterized in that, The oil phase is cyclohexane or n-hexane.

19. The selective hydrogenation method for cracked gasoline fractions as described in claim 7, characterized in that, The surfactant is a nonionic surfactant.

20. The selective hydrogenation method for cracked gasoline fractions as described in claim 19, characterized in that, The nonionic surfactant is polyethylene glycol octylphenyl ether or hexadecyltrimethylammonium bromide.

21. The selective hydrogenation method for cracked gasoline fractions as described in claim 7, characterized in that, The co-surfactant is a C4-C6 organic alcohol.

22. The selective hydrogenation method for cracked gasoline fractions as described in claim 21, characterized in that, The co-surfactant is n-butanol and / or n-pentanol.

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