CN114073965A

CN114073965A - Preparation method of selective hydrogenation catalyst

Info

Publication number: CN114073965A
Application number: CN202010815223.9A
Authority: CN
Inventors: 展学成; 孙利民; 马好文; 王斌; 胡晓丽; 王书峰; 边虎; 张铁晶; 谢培思; 吕龙刚
Original assignee: Petrochina Co Ltd
Current assignee: Petrochina Co Ltd
Priority date: 2020-08-13
Filing date: 2020-08-13
Publication date: 2022-02-22

Abstract

A selective hydrogenation catalyst preparation method, the carrier of the catalyst is alumina or mainly alumina, and have bimodal pore distribution structure, the active component of catalyst at least contains Pd, W, Ni, Cu, characterized by that wherein Ni, Cu are supported by way of microemulsion, make Ni, Cu distribute in the macropore of the carrier mainly; 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. Can be used for the selective hydrogenation process of pyrolysis gasoline fraction, and has good hydrogenation activity, excellent selectivity and high coking resistance.

Description

Preparation method of selective hydrogenation catalyst

Technical Field

The invention relates to a preparation method of a selective hydrogenation catalyst, in particular to a preparation method of a pyrolysis gasoline fraction selective hydrogenation catalyst.

Background

The pyrolysis gasoline is an important byproduct of a device for preparing ethylene by steam cracking, the yield is 50-80 percent (mass fraction) of the ethylene production capacity, wherein the content of aromatic hydrocarbon is more than 50 percent, and the pyrolysis gasoline is an important raw material for extracting the aromatic hydrocarbon. The pyrolysis gasoline contains a large amount of unsaturated hydrocarbons (diene, monoene) and impurities such as sulfur and nitrogen, so that the pyrolysis gasoline has poor stability and is easy to generate colloid, and the impurities such as the unsaturated hydrocarbons and the sulfur and nitrogen can greatly reduce the selectivity of an extracting agent during the extraction of aromatic hydrocarbons and seriously affect the purity and chromaticity of aromatic hydrocarbon products, so that the pyrolysis gasoline can be used as a raw material for the extraction of the aromatic hydrocarbons after the impurities such as the olefin and the sulfur and nitrogen are removed through hydrofining. At present, two-stage hydrofining technology is commonly adopted at home and abroad to remove impurities such as olefin, sulfur, nitrogen and the like in pyrolysis gasoline, thereby producing qualified aromatic extraction raw materials.

The first-stage hydrogenation is mainly to selectively hydrogenate diolefin and alkenyl aromatic hydrocarbon into mono-olefin and alkyl aromatic hydrocarbon under the condition of low temperature; the second-stage hydrogenation belongs to a full hydrogenation reaction, residual olefin, sulfur, nitrogen and other impurities are removed at high temperature, and the hydrogenated product is sent to a downstream aromatic extraction device for further rectification and separation of benzene, toluene and xylene products.

At present, the first-stage hydrogenation catalyst for the pyrolysis gasoline in the industry mainly comprises two catalysts, namely a palladium catalyst and a nickel catalyst, and the palladium catalyst has the advantages of low starting temperature, high hydrogenation activity, high space velocity, long running period, strong regeneration capacity and the like.

In the actual hydrogenation reaction process, when the palladium catalyst catalyzes the selective hydrogenation of diolefin, unsaturated hydrocarbon in the raw material can be polymerized on an acid center of the catalyst to generate a high polymer with a wider molecular weight, commonly called as 'colloid', the colloid is further adsorbed on the surface of the catalyst and further forms coking to block a catalyst pore channel, so that reactants cannot diffuse to the surface of an active center of the catalyst, and the activity of the catalyst is reduced; meanwhile, impurities such as sulfur, arsenic and the like in the raw materials are easily adsorbed on the active center, so that the catalyst is inactivated.

ZL201010124912.1 discloses a selective hydrogenation catalyst for pyrolysis gasoline and a preparation method thereof. The active component comprises a main active component palladium and an auxiliary active component, wherein the palladium content is 0.01-1.0 wt% of the total weight of the carrier; the auxiliary active component is one or more of Sn, Pb, Cu, Ga, Zn, Ag, Sb, Mn, Co, Mo and W, and the content of the auxiliary active component is 0-3.0 wt% of the total weight of the carrier. The invention adopts ionizing radiation to reduce the precursor of the metal active component or the oxide of the calcined precursor of the metal active component to obtain the pyrolysis gasoline selective hydrogenation catalyst loaded with the metal active component on the carrier, and the prepared catalyst improves the utilization rate of the main active component Pd.

ZL200510117439.3 provides an alkyne and diene selective hydrogenation catalyst, a preparation method and application thereof. The catalyst of the invention comprises an inert carrier selected from silicon carbide, talcum powder, refractory clay and an alumina coating; the main catalysts in the alumina coating are palladium, silver and bismuth, and at least one of copper, zinc, alkali metal, alkaline earth metal and rare earth element; the alumina coating is coated on the outer surface of the inert carrier, the thickness of the alumina coating is 10-500 micrometers, and the specific surface area of the alumina coating is 1-200 m²(ii)/g; the weight ratio of palladium to the inert carrier is 0.001-1.0%.

ZL200810119385.8 discloses a non-noble metal supported selective hydrogenation catalyst and a preparation method and application thereof, and the catalyst comprises a carrier, and a main active component and an auxiliary active component which are supported on the carrier, and is characterized in that the main active component is Ni, the auxiliary active component is 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, the average grain diameter is less than 10nm, and the carrier is a non-oxidative porous material; the catalyst is prepared by a micro-emulsion method and is used for removing alkyne in a selective hydrogenation manner by using carbon dioxide, and the selectivity of the catalyst is to be further improved.

ZL201110234140.1 provides a hydrogenation catalyst comprising an alumina-titania composite support and metallic palladium and metallic molybdenum or metallic tungsten supported on said composite support; the weight ratio of the alumina to the titanium oxide in the composite carrier is 3: 1-6: 1; the content of the metal palladium is 0.2-0.4% based on the weight of the catalyst; the weight ratio of the metal palladium to the metal molybdenum or the metal tungsten is 1: 0.8-2, and the catalyst is used for hydrogenation of hydrocarbon-modified petroleum resin.

ZL201410118993.2 relates to a catalyst for selective hydrogenation of pyrolysis gasoline, which comprises attapulgite-titanium oxide-alumina composite oxide serving as a carrier, and a metal palladium active component and a rare earth metal auxiliary agent metal which are loaded on the composite oxide carrier, wherein the content of metal palladium is 0.25-0.35 wt%, the content of auxiliary agent metal is 0-3 wt%, and the content of alumina-based attapulgite in the carrier is 0.1-3 wt% and the content of titanium oxide is 5-20 wt%. Finally, it relates to a method for preparing the composite oxide carrier by using cocurrent coprecipitation method.

US4484015A provides a composition and method comprising palladium and silver, each in an amount sufficient to effect substantially selective hydrogenation of certain unsaturated hydrocarbons. For the selective hydrogenation of highly unsaturated hydrocarbons (e.g., alkynes or diolefins) to less unsaturated hydrocarbons (e.g., alkenes or monoolefins). The composition further includes an alkali metal-containing compound, such as potassium fluoride. However, the activity of the catalyst is to be further improved.

ZL200810114744.0 relates to an unsaturated hydrocarbon selective hydrogenation catalyst and a preparation method thereof. The catalyst takes alumina as a carrier, and is characterized by comprising the following components by taking the total weight of the catalyst as a reference: the palladium is used as an active component, the content of the palladium is 0.1-1.0%, the content of rare earth metal is 0.1-6.0%, the content of alkaline earth metal is 0.1-4.0%, fluorine can be contained, the content of the fluorine is 0-3.0%, and the balance is an alumina carrier. The alumina carrier is theta or mixed crystal form Al₂O₃The theta crystal form is the main crystal form. The catalyst is suitable for the first-stage selective hydrogenation process of full fraction pyrolysis gasoline and also suitable for the selective hydrogenation process of unsaturated hydrocarbon in other distillate oil. The catalyst improves the impurity resistance and the coking resistance of the catalyst by adding rare earth, alkaline earth metal and fluorine, but the selectivity of the catalyst is not ideal.

The catalyst prepared by the method adopts the catalyst with single pore size distribution, and is influenced by internal diffusion in the fixed bed reaction process, and the selectivity of the catalyst is relatively poor. The carrier with bimodal pore distribution can reduce the influence of internal diffusion and improve the selectivity of the catalyst while ensuring the high activity of the catalyst.

ZL201410655649.7 provides a diolefin selective hydrogenation catalyst and a preparation method thereof. The carrier of the catalyst is carboxyl functionalized cascade-hole FZIF-8, and the active component is palladium with the content of 0.1-10%; the invention also provides a preparation method of the diolefin selective hydrogenation catalyst. The carrier provided by the invention has a step pore structure, so that carboxyl groups have accessibility, active components can interact with the carboxyl groups, high dispersion of the active components is realized, and agglomeration and loss of the active components in the reaction process are prevented.

The hydrogenation catalyst provided by patent ZL200810223451.6 takes Pd and Ag bimetal as active components, and is characterized in that the catalyst has bimodal pore distribution, the radius of the largest part of small pores is 2-50 nm, the radius of the largest part of large pores is 100-500 nm, wherein the content of Pd is 0.02-0.1%, the content of Ag is 10-1/1, the catalyst can also contain alkali metal and/or alkaline earth metal, the content is 0-5.0%, and the specific surface of the catalyst isIs 30 to 90m²The pore volume is 0.3 to 0.6 mL/g. Because the catalyst is in bimodal pore distribution, the catalyst has good hydrogenation activity, good selectivity, large ethylene increment and obvious economic benefit. The catalyst is characterized by having bimodal pore distribution, wherein the radius of the small pore part can be 2-50 nm at most, and the radius of the large pore part can be 100-500 nm at most.

In the selective hydrogenation reaction of pyrolysis gasoline fraction, the formation of colloid and the coking of catalyst are important factors influencing the service life of catalyst. The activity, selectivity and service life of the catalyst form the overall performance of the catalyst, and the methods listed above provide better ways for improving the activity and selectivity of the catalyst, but do not solve the problem that the catalyst is easy to coke, or solve the problem that the catalyst is easy to generate colloid and coke, but do not solve the problem of selectivity. Although the carrier with a macroporous structure can improve the selectivity, larger molecules generated by polymerization and chain growth reaction are easy to accumulate in the macropores of the carrier, so that the catalyst is coked and inactivated, and the service life of the catalyst is influenced.

ZL201310114077.7 discloses a hydrogenation catalyst, the active components in the catalyst are Pd, Ag and Ni, wherein the Pd and the Ag are loaded by adopting an aqueous solution impregnation method, and the Ni is loaded by adopting a W/O microemulsion impregnation method. After the method is adopted, Pd/Ag and Ni are positioned in pore channels with different pore diameters, green oil generated by reaction is saturated and hydrogenated in a large pore, and the coking amount of the catalyst is reduced. However, the reduction temperature of Ni is usually about 500 ℃, and the reduced Pd atoms are easy to gather at the temperature, so that the activity of the catalyst is greatly reduced, the equivalent amount of active components needs to be greatly increased to compensate the activity loss, and the selectivity is reduced.

Disclosure of Invention

The invention aims to provide a preparation method of a selective hydrogenation catalyst, in particular to a preparation method of a pyrolysis gasoline fraction selective hydrogenation catalyst.

A selective hydrogenation catalyst preparation method, the carrier of the catalyst is alumina or mainly alumina, and have bimodal pore distribution structure, the active component of the catalyst contains Pd, W, Ni, Cu at least, wherein Ni, Cu are supported by way of microemulsion, make Ni, Cu distribute in the macropore of the carrier mainly; w is loaded by a solution method; the Pd is loaded by adopting two modes of a solution method and a microemulsion method, wherein most of the Pd is loaded by adopting the solution method, and a small part of the Pd is loaded by adopting the microemulsion method.

In the catalyst prepared by the method, the selective hydrogenation reaction of the diolefin occurs in a main active center consisting of Pd and W; ni and Cu are soaked in the macropores of the carrier in the form of microemulsion, and colloid generated in the reaction is subjected to saturated hydrogenation on an active center consisting of Cu and Ni.

For hydrogenation reaction, generally, before the catalyst is applied, the hydrogenation catalyst needs to be reduced first to ensure that the active component exists in a metallic state, so that the catalyst can have hydrogenation activity. Because activation is a high temperature calcination process during catalyst preparation, the metal salt decomposes to metal oxides, which form clusters, which are typically nano-sized. Different oxides need to be reduced at different temperatures due to different chemical properties. However, for nano-sized metals, a critical temperature is about 200 ℃, and above this temperature, the metal particles will aggregate very significantly. Therefore, the reduction temperature of the active component is very important for the hydrogenation catalyst.

The effect of Cu is to form Ni/Cu alloy in the roasting process, which not only can improve the performance of the catalyst, but also the inventor finds that the reduction temperature of nickel is effectively reduced in the reduction process, and the polymerization of Pd at high temperature is reduced. The reduction temperature of Ni can be reduced by loading Cu and Ni together, because the NiO is required to be completely reduced independently, the reduction temperature generally needs to reach 450-500 ℃, Pd can be caused to agglomerate at the temperature, and after the Cu/Ni alloy is formed, the reduction temperature can be reduced by more than 100 ℃ and reaches 350 ℃ compared with the reduction temperature of pure Ni, so that the agglomeration of Pd in the reduction process is relieved.

The inventor unexpectedly finds that a small amount of Pd is loaded on the surface of the Ni/Cu alloy, and the reduction temperature of Ni can be greatly reduced and can reach below 200 ℃ and as low as 150 ℃.

The inventor finds that: the selective hydrogenation reaction of the pyrolysis gasoline occurs in a main active center consisting of Pd and W, and macromolecules such as colloid and the like produced in the reaction easily enter macropores of the catalyst. For example, a Ni/Cu component is loaded in a large pore of the catalyst and has a saturated hydrogenation function, and the colloid component can perform a saturated hydrogenation reaction at an active center consisting of Ni/Cu. Because the double bonds are saturated by hydrogenation, the colloid components can not generate polymerization reaction any more or the polymerization reaction rate is greatly reduced, the chain growth reaction is terminated or delayed, a fused ring compound with huge molecular weight can not be formed, and the fused ring compound is easily carried out of the reactor by materials, so the coking degree on the surface of the catalyst is greatly reduced, and the service life of the catalyst is greatly prolonged.

The method for controlling the Ni/Cu alloy to be positioned in the catalyst macropores is characterized in that Ni/Cu is loaded in a micro-emulsion mode, and the grain diameter of the micro-emulsion is larger than the pore diameter of carrier micropores and smaller than the maximum pore diameter of macropores. Ni and Cu metal salts are contained in the microemulsion and are difficult to enter the pore channels of the carrier with smaller size due to steric resistance, so that Ni and Cu are mainly concentrated in macropores.

In the invention, the load of Pd is loaded by two modes, namely a solution method and a microemulsion method, wherein most of Pd is loaded by the solution, a small part of Pd is loaded by the microemulsion method, the particle size of the microemulsion is controlled to be larger than the pore size of small pores of a carrier and smaller than the pore size of large pores of the carrier when the microemulsion method is loaded, so that the part of Pd is distributed in the large pores of the carrier, the amount of Pd loaded by the microemulsion method is 1/100-1/200 of the content of Ni and Cu, and the step of loading Pd by the microemulsion method is after the step of loading Ni and Cu by the microemulsion method.

The carrier adopted by the invention is required to have a bimodal pore distribution structure, the invention does not particularly limit the distribution range of large pores and small pores of bimodal pore distribution, and can be selected according to reaction characteristics, such as raw materials, process conditions, catalyst active components and the like, and the carrier is particularly recommended to be large pores with the pore diameter of 50-300 nm, and the pore diameter of small pores is 10-30 nm. For the same reason, the present invention is not particularly limited to the composition of Pd, W, Ni, Cu in the active component. Carrier Al₂O₃The crystal form is alpha, theta or a mixed crystal form thereof; the preferred catalyst support preferably contains at least 80% alumina.

The catalyst is impregnated with Ni/Cu load in microemulsion form during the preparation process. The Pd loading is impregnated by two methods, namely a solution method and a microemulsion method, and the W loading can be carried out by a solution saturation impregnation method.

The invention is not particularly limited to the process of loading Ni, Cu and Pd in a microemulsion mode, and Ni, Cu and Pd can be distributed in the macropores of the carrier as long as the particle size of the microemulsion can form a microemulsion which is larger than the pore size of the small pores of the carrier and smaller than the pore size of the large pores of the carrier.

The invention also proposes a method, wherein the microemulsion mode loading process comprises the following steps: dissolving precursor salt in water, adding oil phase, surfactant and cosurfactant, and stirring to form microemulsion, wherein the oil phase is alkane or cycloalkane, the surfactant is ionic surfactant and/or nonionic surfactant, and the cosurfactant is organic alcohol.

The kind and addition amount of the oil phase, the surfactant and the co-surfactant are not particularly limited in the present invention, and can be determined according to the pore structures of the precursor salt and the carrier.

The oil phase recommended by the invention is saturated alkane or cycloalkane, preferably C6-C8 saturated alkane or cycloalkane, preferably cyclohexane and n-hexane; the surfactant is an ionic surfactant and/or a nonionic surfactant, preferably the nonionic surfactant, and more preferably polyethylene glycol octyl phenyl ether or cetyl trimethyl ammonium bromide; the cosurfactant is organic alcohol, preferably C4-C6 alcohol, more preferably n-butanol and/or n-pentanol.

In the microemulsion, the recommended weight ratio of the water phase to the oil phase is 1.5-2.5, the weight ratio of the surfactant to the oil phase is 0.2-0.7, the weight ratio of the surfactant to the cosurfactant is 1-1.2, and the particle size of the microemulsion is controlled to be larger than 30nm and smaller than 300 nm; the preferable conditions are that the weight ratio of the water phase to the oil phase is 2-2.5, the weight ratio of the surfactant to the oil phase is 0.4-0.5, and the particle size of the microemulsion is controlled to be more than 30nm and less than 100 nm. The microemulsion has grain size greater than the maximum pore size of the small pores and smaller than the minimum pore size of the large pores, so that the microemulsion is more favorable for loading the active components, and the active components, particularly Ni and Cu, in the prepared catalyst are more uniformly distributed.

The solution of Pd can be loaded before or after the step of loading Ni and Cu in the microemulsion; the microemulsion loading of Pd is carried out after the step of loading Ni and Cu by the microemulsion; the support of W follows the solution loading step of Pd. In the two loading processes by the two microemulsion methods, the particle size of the W/O microemulsion may be the same or different, preferably the same.

The invention also provides a more specific preparation method of the selective hydrogenation catalyst, which comprises the following steps:

(1) dissolving precursor salt of Ni and Cu in water, adding metered oil phase, surfactant and cosurfactant, fully stirring to form microemulsion, controlling the particle size of the microemulsion to be larger than the aperture of small holes of a carrier and smaller than the aperture of large holes of the carrier, adding the carrier into the prepared microemulsion, soaking for 0.5-4 hours, filtering to remove residual liquid, drying for 1-6 hours at 80-120 ℃, and roasting for 2-8 hours at 400-600 ℃. Obtaining a semi-finished product catalyst A;

(2) dissolving a precursor salt of Pd in water, adjusting the pH value to 1.8-2.8, adding the semi-finished catalyst A into a Pd salt solution, soaking and adsorbing for 0.5-4 h, drying at 100-120 ℃ for 1-4 h, and roasting at 400-550 ℃ for 2-6 h to obtain a semi-finished catalyst B;

(3) taking deionized water with the saturated water absorption of 80-110 of the semi-finished catalyst B, adding ammonium metatungstate to completely dissolve the deionized water, soaking the semi-finished catalyst B in the prepared solution, shaking uniformly, precipitating for 0.5-2 h, drying at 100-120 ℃ for 1-4 hours, and roasting at 400-550 ℃ for 2-6 hours to obtain a semi-finished catalyst C;

(4) dissolving Pd precursor salt in water, adding metered oil phase, surfactant and cosurfactant, fully stirring to form microemulsion, controlling the particle size of the microemulsion to be larger than the maximum pore diameter of the small pores and smaller than the maximum pore diameter of the large pores, adding the semi-finished catalyst C into the prepared microemulsion, soaking for 0.5-4 hours, filtering out residual liquid, drying for 1-6 hours at 80-120 ℃, and roasting for 2-8 hours at 400-600 ℃ to obtain the catalyst.

For one sample, the conditions of step (1) and step (4) may be the same, or different, preferably the same, so as to ensure that Pd is supported on the surface of the Ni/Cu alloy.

In the above 4 steps, the loading of step (3) W is performed after the loading of Pd by the solution method in step (2); step 4 is after step (1).

The Pd loading by the solution method and the Ni/Cu loading by the microemulsion method can be carried out in any order.

In the step (2), the solution method loading of Pd can adopt wet supersaturated impregnation.

In the step (3), the loading of W can adopt a solution saturation impregnation method.

The carrier in the step (1) is alumina or mainly alumina and Al₂O₃The crystal form is preferably alpha, theta or a mixed crystal form thereof. The alumina content in the catalyst carrier is preferably above 80%, and the carrier may also contain other metal oxides such as magnesia, titania, etc.

The carrier in the step (1) can be spherical, cylindrical, clover-shaped, dentate spherical, clover-shaped and the like.

The ratio of the large pore volume to the small pore volume of the carrier in the step (1) is not limited and is determined according to the loading content of the active component.

The precursor salts of Ni, Cu, W and Pd in the above steps are soluble salts, and can be nitrates, chlorides or other soluble salts thereof.

The mass ratio of Ni to Cu in the step (1) is preferably 10:1 to 1: 1.

In the steps (1) and (4), the mass ratio of Ni + Cu to Pd is 100: 1-200: 1.

The reduction temperature of the catalyst of the invention before use is preferably 150-200 ℃.

The catalyst obtained by the method of the invention has the following characteristics: at the beginning of the hydrogenation reaction, the hydrogenation activity of palladium is high and is mainly distributed in the small holes, so that the selective hydrogenation reaction of diolefin mainly occurs in the small holes. With the prolonging of the operation time of the catalyst, a part of by-products with larger molecular weight are generated on the surface of the catalyst, and due to the larger molecular size, the substances enter the macropores more frequently and the retention time is longer, the hydrogenation reaction of double bonds can be generated under the action of the nickel catalyst, so that saturated hydrocarbon or aromatic hydrocarbon without isolated double bonds is generated, and substances with larger molecular weight are not generated any more. The catalyst obtained by the method can greatly reduce the reduction temperature of the catalyst to 150-200 ℃ at the lowest.

When the method is used for preparing the pyrolysis gasoline selective hydrogenation catalyst, the mass of the catalyst is 100%, the content of Pd is 0.15-0.50 wt%, preferably 0.25-0.40 wt%, the mass ratio of W to Pd is 1-5: 1, preferably 1-3: 1, the content of Ni is 0.5-5 wt%, preferably 0.5-3%, the mass ratio of Cu to Ni is 0.1-1: 1, and the amount of Pd loaded by a microemulsion method is 1/100-1/200 of the content of Ni and Cu.

The present inventors have also found that when the catalyst is used, even if the reaction product contains a large amount of heavy fraction, and the amount of catalyst gum formation may be greatly increased, the catalyst activity and selectivity do not tend to decrease.

Drawings

FIG. 1 shows the Temperature Programmed Reduction (TPR) of samples prepared by loading Cu/Ni and Pd-Cu/Ni by a microemulsion method.

Detailed Description

The following examples illustrate the invention in detail: the present example is carried out on the premise of the technical scheme of the present invention, and detailed embodiments and processes are given, but the scope of the present invention is not limited to the following examples, and the experimental methods without specific conditions noted in the following examples are generally performed according to conventional conditions.

The raw material sources are as follows: pyrolysis gasoline was obtained from landau petrochemical ethylene plants.

The analysis method comprises the following steps:

microemulsion particle size distribution: analyzing the particle size distribution of the Ni/Cu alloy microemulsion and the palladium microemulsion by adopting a dynamic light scattering particle size analyzer;

the method for measuring the composition content of the catalyst comprises the following steps: analyzing by using national standard GB/T15337 of atomic absorption Spectroscopy rules and GB19723 of chemical reagent GB/T15337 of flame atomic absorption Spectroscopy rules;

specific surface area, pore diameter: measured by GB/T21650 standard;

diene value: measured by the method of UOP 326-2008;

bromine number: the SH/T0236-92 standard is adopted for determination.

Water content: measuring by using GB/T11133-89 standard;

sulfur content: measuring by adopting a WK-2B micro coulometer;

the colloid content is as follows: measured by the method of GB 8019-2008.

The invention is further illustrated by the following examples, which are not to be construed as limiting the invention thereto.

Example 1

Preparation of a catalyst carrier: a commercial bimodal pore distribution spherical alumina carrier with the diameter of 3-4 mm is adopted, after the carrier is roasted at 955 ℃ for 4 hours, the pore size distribution ranges are 11-28 nm and 55-280 nm respectively, the water absorption rate is 68%, and the specific surface area is 142m²Weighing 150g of the carrier.

Preparing a catalyst:

(1) dissolving nickel nitrate and copper nitrate in 80g of water, adding 40g of n-pentane, 18g of CTAB and 16g of n-octanol, fully stirring to form a microemulsion, adding the carrier into the prepared microemulsion, soaking for 0.5h, filtering out residual liquid, and washing with deionized water to be neutral. Drying at 80 deg.C for 6 hr, and calcining at 590 deg.C for 2 hr to obtain semi-finished catalyst C1-A.

(2) Palladium chloride was dissolved in 75g of water, and 48g of n-pentane, 20g of CTAB, and 17g of n-octanol were added thereto and sufficiently stirred to form a microemulsion. And (2) soaking the semi-finished product C1-A prepared in the step (1) in the prepared microemulsion for 0.5h, filtering out residual liquid, and washing with deionized water to be neutral. Drying at 60 deg.C for 6 hr, and calcining at 450 deg.C for 8 hr to obtain semi-finished catalyst C1-B.

(3) Preparing active component impregnation liquid by palladium chloride, adjusting the pH value to 2.6, adding the semi-finished catalyst C1-B prepared in the step (2) into a Pd salt solution, drying for 2h at 120 ℃ after impregnation and adsorption for 1h, and roasting for 5h at 410 ℃ to obtain the semi-finished catalyst C1-C.

(4) Completely dissolving ammonium metatungstate into an impregnation solution, impregnating in an equal volume, impregnating a semi-finished catalyst C1-C in the prepared solution, shaking uniformly, precipitating for 2h, drying at 120 ℃ for 1h, and roasting at 500 ℃ for 4h to obtain the desired catalyst C1, wherein the catalyst composition is shown in Table 1.

The particle sizes of the microemulsions prepared in the steps (1) and (2) are respectively 61 nm and 50nm measured by a dynamic light scattering method.

And (3) catalyst reduction: before use, the mixture is placed in a fixed bed reaction device and is subjected to reduction treatment for 8 hours by pure hydrogen at the temperature of 200 ℃.

Comparative example 1

Comparative example 1 catalyst D1 was prepared by the same method, composition and reduction treatment as example 1 catalyst C1, except that the Pd microemulsion prepared in step (2) had a smaller particle size, i.e.:

dissolving palladium chloride in 70g of water, adding 40g of n-pentane, 24g of CTAB and 22g of n-octanol, fully stirring to form a microemulsion, and measuring the particle size of the prepared microemulsion to be 20nm by a dynamic light scattering method. The other procedures were the same, and catalyst D1 of comparative example 1 was finally obtained.

Example 2

Preparation of a catalyst carrier: a commercial bimodal pore distribution spherical alumina carrier with the diameter of 3-4 mm is adopted, after roasting for 4 hours at 1070 ℃, the pore size distribution ranges are 12-30 nm and 85-300 nm respectively, the water absorption rate is 63 percent, and the specific surface area is 70m²Weighing 150g of the carrier.

Preparing a catalyst:

(1) preparing active component impregnation liquid by palladium chloride, adjusting the pH value to 2.1, adding the carrier into a Pd salt solution, impregnating and adsorbing for 3 hours, drying for 4 hours at 100 ℃, and roasting for 2 hours at 550 ℃ to obtain a semi-finished catalyst C2-A.

(2) Completely dissolving ammonium metatungstate into an impregnation solution, impregnating in an equal volume, impregnating the semi-finished catalyst C2-A in the prepared solution, shaking uniformly, precipitating for 0.5h, drying at 110 ℃ for 2h, and roasting at 400 ℃ for 6h to obtain the semi-finished catalyst C2-B.

(3) Dissolving nickel nitrate and copper nitrate in 80g of water, adding 38g of cyclohexane, 17g of TritonX-100 and 15g of n-butanol, and fully stirring to form microemulsion. Adding the semi-finished catalyst C2-B prepared in the step (2) into the prepared microemulsion, soaking for 4h, filtering out residual liquid, and washing with deionized water to be neutral. Drying at 100 deg.C for 4 hr, and calcining at 400 deg.C for 8 hr to obtain semi-finished catalyst C2-C.

(4) Palladium chloride is dissolved in 80g of water, 38g of cyclohexane, 17g of Triton X-100 and 15g of n-butanol are added and fully stirred to form microemulsion. And (4) soaking the semi-finished product C2-C prepared in the step (3) in the prepared microemulsion for 4 hours, filtering out residual liquid, and washing the residual liquid to be neutral by deionized water. Drying at 120 deg.C for 1h, and calcining at 400 deg.C for 4h to obtain the desired catalyst C2, the catalyst composition is shown in Table 1.

And (4) determining the particle size of the micro-emulsion prepared in the steps (3) and (4) to be 73nm by using a dynamic light scattering method.

And (3) catalyst reduction: before use, the mixture is placed in a fixed bed reaction device and is subjected to reduction treatment for 8 hours by pure hydrogen at the temperature of 150 ℃.

Comparative example 2

Comparative example 2 catalyst D2 was prepared by the same method, composition and reduction treatment as example 2 catalyst C2, except that the Pd microemulsion prepared in step (4) had a larger particle size, i.e.:

dissolving palladium chloride in 80g of water, adding 20g of cyclohexane, 8g of TritonX-100 and 8g of n-butanol, fully stirring to form a microemulsion, and determining the particle size of the prepared microemulsion to be 400nm by a dynamic light scattering method. The other procedures were the same, and catalyst D2 of comparative example 2 was finally obtained.

Example 3

Preparation of a catalyst carrier: adopting a commercial dual-peak pore distribution clover-shaped alumina carrier with the diameter of 2.5-3.5 mm, roasting at 1010 ℃ for 4 hours, wherein the pore size distribution ranges are respectively 10-28 nm and 58-290 nm, the water absorption rate is 68%, and the specific surface area is 105m²Weighing 150g of the carrier.

Preparing a catalyst:

(1) preparing active component impregnation liquid by palladium chloride, adjusting the pH value to 2.0, adding the carrier into a Pd salt solution, impregnating and adsorbing for 0.5h, drying for 4h at 100 ℃, and roasting for 4h at 440 ℃ to obtain a semi-finished catalyst C3-A.

(2) Nickel nitrate, copper nitrate were dissolved in 75g of water, 48g of cyclohexane, 20g of CTAB, 17g of n-pentanol were added and stirred thoroughly to form a microemulsion. Adding the semi-finished catalyst C3-A prepared in the step (1) into the prepared microemulsion, soaking for 3h, filtering out residual liquid, and washing with deionized water to be neutral. Drying at 70 deg.C for 6 hr, and calcining at 470 deg.C for 4 hr to obtain semi-finished catalyst C3-B.

(3) Palladium chloride was dissolved in 80g of water, 40g of n-hexane, 18g of CTAB, and 18g of n-pentanol were added thereto, and stirred sufficiently to form a microemulsion. And (3) soaking the semi-finished product C3-B prepared in the step (2) in the prepared microemulsion for 2 hours, filtering out residual liquid, and washing the residual liquid to be neutral by deionized water. Drying at 80 deg.C for 4 hr, and calcining at 520 deg.C for 3 hr to obtain semi-finished catalyst C3-C.

(4) Completely dissolving ammonium metatungstate into an impregnation solution, impregnating in an equal volume, impregnating a semi-finished catalyst C3-C in the prepared solution, shaking uniformly, precipitating for 1h, drying at 120 ℃ for 2h, and roasting at 490 ℃ for 4h to obtain the desired catalyst C3, wherein the catalyst composition is shown in Table 1.

The particle diameters of the micro-emulsions prepared in the steps (2) and (3) are respectively 50nm and 60nm by dynamic light scattering method.

Comparative example 3

Comparative example 3 catalyst D3 was prepared by the same method, composition and reduction as example 3 catalyst C3, except that palladium and tungsten were simultaneously supported in the solution process, and the adjusted catalyst was prepared by the following steps:

palladium, tungsten solution load → nickel copper alloy microemulsion load → palladium microemulsion load

All the parameters of the preparation process were the same, and finally the catalyst D3 of comparative example 3 was obtained.

Comparative example 4

Comparative example 4 catalyst D4 was prepared by the same method, composition and reduction as example 3 catalyst C3 except that the microemulsions of palladium, nickel and copper were simultaneously supported and the adjusted catalyst was prepared by the following steps:

palladium solution load → palladium nickel copper alloy simultaneous microemulsion load → tungsten solution load

All the parameters of the preparation process were the same, and finally, catalyst D6 of comparative example 6 was obtained.

Comparative example 5

Comparative example 5 the preparation method, composition and reduction treatment of catalyst D5 were the same as those of catalyst C3 of example 3, except that the microemulsion method copper palladium was first loaded, the microemulsion method nickel was then loaded, and the adjusted catalyst preparation steps were:

palladium solution load → copper-palladium alloy microemulsion load → nickel microemulsion load → tungsten solution load

All the parameters of the preparation process were the same, and finally the catalyst D5 of comparative example 5 was obtained.

Example 4

Preparation of a catalyst carrier: the method adopts a commercially available bimodal pore distribution dentate spherical alumina carrier with the diameter of 3-4 mm, after roasting at 1060 ℃ for 4 hours, the pore size distribution ranges are 14-29 nm and 85-300 nm respectively, the water absorption rate is 66%, and the specific surface area is 86m²Weighing 150g of the carrier.

Preparing a catalyst:

(1) dissolving nickel nitrate and copper nitrate in 80g of water, adding 40g of cyclohexane, 18g of Triton X-100 and 15g of n-butyl alcohol, and fully stirring to form microemulsion. Adding the carrier into the prepared microemulsion, soaking for 1h, filtering out residual liquid, and washing with deionized water to be neutral. Drying at 80 deg.C for 3 hr, and calcining at 470 deg.C for 4 hr to obtain semi-finished catalyst C4-A.

(2) Preparing active component impregnation liquid by palladium chloride, adjusting the pH value to 2.2, adding the semi-finished catalyst C4-A prepared in the step (1) into a Pd salt solution, drying for 4h at 100 ℃ after impregnation and adsorption for 2h, and roasting for 2h at 440 ℃ to obtain the semi-finished catalyst C4-B.

(3) Palladium chloride is dissolved in 80g of water, 40g of cyclohexane, 18g of Triton X-100 and 15g of n-butanol are added and stirred sufficiently to form a microemulsion. And (3) soaking the semi-finished product C4-B prepared in the step (2) in the prepared microemulsion for 2 hours, filtering out residual liquid, and washing the residual liquid to be neutral by deionized water. Drying at 80 deg.C for 3h, and calcining at 510 deg.C for 4h to obtain semi-finished catalyst C4-C.

(4) Completely dissolving ammonium metatungstate into an impregnation solution, impregnating in an equal volume, impregnating a semi-finished catalyst C4-C in the prepared solution, shaking uniformly, precipitating for 1h, drying at 120 ℃ for 2h, and roasting at 460 ℃ for 4h to obtain the desired catalyst C4, wherein the catalyst composition is shown in Table 1.

The particle size of the micro-emulsion prepared in the steps (1) and (3) is 65nm determined by a dynamic light scattering method.

Comparative example 6

Comparative example 6 catalyst D6 was prepared by the same method, composition and reduction treatment as example 4 catalyst C4, except that the copper nickel in step (1) was supported by a solution method, namely:

the nickel nitrate and the copper nitrate were completely dissolved in the impregnation solution, and the impregnation was carried out in the same volume, and the other preparation processes were the same, thereby finally obtaining catalyst D6 of comparative example 6.

Comparative example 7

Comparative example 7 catalyst D7 was prepared by the same method, composition and reduction treatment as example 4 catalyst C4, except that the catalyst support used was a single pore size distribution support, i.e.:

the method adopts a commercial clover-shaped alumina carrier with unimodal pore distribution, the diameter is 2-3 mm, after roasting at 1080 ℃ for 4 hours, the pore size distribution range is 12-27 nm, the water absorption rate is 67%, and the specific surface area is 93m²Weighing 150g of the carrier.

All the parameters of the preparation process were the same, and finally, catalyst D7 of comparative example 7 was obtained.

Example 5

Preparation of a catalyst carrier: the method adopts a commercial dual-peak pore distribution cloverleaf alumina carrier with the diameter of 2.5-3.5 mm, after roasting for 4 hours at 1010 ℃, the pore size distribution ranges are 10-28 nm and 75-300 nm respectively, the water absorption rate is 68%, and the specific surface area is 93m²Weighing 150g of the carrier.

Preparing a catalyst:

(1) dissolving nickel nitrate and copper nitrate in 80g of water, adding 40g of n-hexane, 24g of CTAB and 22g of n-amyl alcohol, fully stirring to form a microemulsion, adding the carrier into the prepared microemulsion, soaking for 2 hours, filtering out residual liquid, and washing with deionized water to be neutral. Drying at 60 deg.C for 6 hr, and calcining at 520 deg.C for 3 hr to obtain semi-finished catalyst C5-A.

(2) Preparing active component impregnation liquid by palladium chloride, adjusting the pH value to 2.3, adding the semi-finished catalyst C5-A prepared in the step (1) into a Pd salt solution, drying for 3h at 110 ℃ after impregnation and adsorption for 2h, and roasting for 4h at 460 ℃ to obtain the semi-finished catalyst C5-B.

(3) Completely dissolving ammonium metatungstate into an impregnation solution, impregnating in an equal volume, impregnating the semi-finished catalyst C5-B in the prepared solution, shaking uniformly, precipitating for 1h, drying at 100 ℃ for 4h, and roasting at 550 ℃ for 3h to obtain the semi-finished catalyst C5-C.

(4) Palladium chloride was dissolved in 75g of water, 40g of n-hexane, 18g of CTAB, and 18g of n-pentanol were added thereto, and stirred sufficiently to form a microemulsion. And (4) soaking the semi-finished product C5-C prepared in the step (3) in the prepared microemulsion for 3 hours, filtering out residual liquid, and washing the residual liquid to be neutral by deionized water. Drying at 100 deg.C for 3 hr, and calcining at 580 deg.C for 2 hr to obtain the desired catalyst C5, the composition of which is shown in Table 1.

The particle diameters of the micro-emulsions prepared in the steps (1) and (4) are respectively 60nm and 50nm by dynamic light scattering method.

And (3) catalyst reduction: before use, the mixture is placed in a fixed bed reaction device and is mixed with N₂:H₂1:1 at 200 ℃ for 8 h.

Comparative example 8

Comparative example 8 catalyst D8 was prepared by the same method, composition and reduction treatment as example 5 catalyst C5, except that the particle size of the nickel-copper alloy micro-emulsion prepared in step (1) was smaller than the maximum pore size of the small pores, i.e.:

dissolving nickel nitrate and copper nitrate in 60g of water, adding 48g of n-hexane, 20g of CTAB and 20g of n-amyl alcohol, fully stirring to form a microemulsion, and measuring the particle size of the prepared microemulsion to be 15nm by a dynamic light scattering method. The other procedures were the same, and catalyst D5 of comparative example 5 was finally obtained.

Comparative example 9

Comparative example 9 catalyst D9 was prepared by the same method, composition and reduction as example 5 catalyst C5, except that the solution tungsten was supported before the solution palladium, and the adjusted catalyst was prepared by the steps of:

nickel-copper alloy microemulsion load → tungsten solution load → palladium microemulsion load

All the parameters of the preparation process were the same, and catalyst D9 of comparative example 9 was finally obtained.

Example 6

Preparation of a catalyst carrier: adopting a commercial dual-peak pore distribution clover-shaped alumina carrier with the diameter of 3-4 mm, roasting at 1090 ℃ for 4h, wherein the pore size distribution ranges are 16-30 nm and 87-300 nm respectively, the water absorption rate is 63%, and the specific surface area is 53m²Weighing 150g of the carrier.

Preparing a catalyst:

(1) preparing active component impregnation liquid by palladium chloride, adjusting the pH value to 2.6, adding the carrier into a Pd salt solution, impregnating and adsorbing for 2 hours, drying for 4 hours at 120 ℃, and roasting for 4 hours at 500 ℃ to obtain a semi-finished catalyst C6-A.

(2) Completely dissolving ammonium metatungstate into an impregnation solution, impregnating in an equal volume, impregnating the semi-finished catalyst C6-A in the prepared solution, shaking uniformly, precipitating for 1h, drying at 120 ℃ for 2h, and roasting at 440 ℃ for 4h to obtain the semi-finished catalyst C6-B.

(3) Nickel nitrate and copper nitrate were dissolved in 75g of water, 34g of n-hexane, 15g of CTAB and 13g of n-butanol were added thereto and sufficiently stirred to form a microemulsion. Adding the semi-finished catalyst C6-B prepared in the step (2) into the prepared microemulsion, soaking for 3h, filtering out residual liquid, and washing with deionized water to be neutral. Drying at 120 deg.C for 1h, and calcining at 450 deg.C for 4h to obtain semi-finished catalyst C6-C.

(4) Palladium nitrate was dissolved in 75g of water, 34g of n-hexane, 15g of CTAB, and 13g of n-butanol, and stirred well to form a microemulsion. And (3) soaking the semi-finished product C6-C prepared in the step (3) in the prepared microemulsion for 1h, filtering out residual liquid, and washing the residual liquid to be neutral by deionized water. Drying at 100 deg.C for 4h, and calcining at 450 deg.C for 4h to obtain the desired catalyst C6, the catalyst composition is shown in Table 1.

The particle size of the micro-emulsion prepared in the steps (3) and (4) is 82nm measured by a dynamic light scattering method.

And (3) catalyst reduction: before use, the mixture is placed in a fixed bed reaction device, and is reduced by pure hydrogen at the temperature of 180 ℃ for 8 hours.

Comparative example 10

Comparative example 10 catalyst D10 was prepared by the same method, composition and reduction as example 6 catalyst C6 except that the microemulsion palladium was supported before the microemulsion nickel copper, and the adjusted catalyst was prepared by the following steps:

palladium solution load → tungsten solution load → palladium microemulsion load → nickel-copper microemulsion load

All the parameters of the preparation process were the same, and finally, catalyst D10 of comparative example 10 was obtained.

Example 7

Preparation of a catalyst carrier: a commercially available bimodal pore distribution tooth spherical alumina carrier with the diameter of 3-4 mm is adopted, after the carrier is roasted at 975 ℃ for 4 hours, the pore size distribution ranges are 10-25 nm and 60-280 nm respectively, the water absorption rate is 75 percent, and the specific surface area is 120m²Weighing 150g of the carrier.

Preparing a catalyst:

(1) preparing active component impregnation liquid by palladium chloride, adjusting the pH value to 2.3, adding the carrier into a Pd salt solution, impregnating and adsorbing for 3.5h, drying for 4h at 110 ℃, and roasting for 3h at 480 ℃ to obtain a semi-finished catalyst C7-A.

(2) Nickel nitrate and copper nitrate are dissolved in 74g of water, 30g of cyclohexane, 14g of Triton X-100 and 12g of n-hexanol are added and fully stirred to form microemulsion. Adding the semi-finished catalyst C7-A prepared in the step (1) into the prepared microemulsion, soaking for 4h, filtering out residual liquid, and washing with deionized water to be neutral. Drying at 80 ℃ for 3h, and roasting at 550 ℃ for 3h to obtain a semi-finished catalyst C7-B.

(3) Palladium chloride is dissolved in 74g of water, 30g of cyclohexane, 14g of Triton X-100 and 12g of n-hexanol are added and fully stirred to form a microemulsion. And (3) soaking the semi-finished product C7-B prepared in the step (2) in the prepared microemulsion for 2 hours, filtering out residual liquid, and washing the residual liquid to be neutral by deionized water. Drying at 70 deg.C for 6h, and calcining at 480 deg.C for 4h to obtain semi-finished catalyst C7-C.

(4) Completely dissolving ammonium metatungstate into an impregnation solution, impregnating in an equal volume, impregnating a semi-finished catalyst C7-C in the prepared solution, shaking uniformly, precipitating for 1h, drying at 100 ℃ for 2h, and roasting at 520 ℃ for 3h to obtain the desired catalyst C7, wherein the catalyst composition is shown in Table 1.

The particle size of the micro-emulsion prepared in the steps (2) and (3) is 157nm determined by a dynamic light scattering method.

And (3) catalyst reduction: before use, the mixture is placed in a fixed bed reaction device and is subjected to reduction treatment for 5 hours by pure hydrogen at the temperature of 150 ℃.

Comparative example 11

Comparative example 11 the preparation method, composition and reduction treatment of catalyst D11 were the same as those of catalyst C7 of example 7, except that the microemulsion method nickel palladium was first loaded, and the microemulsion method copper was then loaded, and the adjusted catalyst preparation steps were:

palladium solution load → nickel palladium microemulsion load → copper microemulsion load → tungsten solution load

All the parameters of the preparation process were the same, and catalyst D11 of comparative example 11 was finally obtained.

Table 1 example catalyst composition

The catalyst has the following performance when applied to pyrolysis gasoline fraction selective hydrogenation reaction:

the pyrolysis gasoline fraction properties are shown in table 2.

TABLE 2 pyrolysis gasoline cut feedstock Properties

The catalyst was evaluated in a single-stage adiabatic fixed bed reactor, and the catalyst loading was 100 mL.

Examples 1-3, 5-7 and corresponding comparative examples 1-5, 8-11 used a pyrolysis gasoline C6-C7 cut, the reaction process conditions: fresh material airspeed of 2.0h^-1The operating pressure is 2.8MPa, the volume ratio of hydrogen to oil is 200:1, the dilution ratio of the product to the pure raw material is 2:1, and the inlet temperature of the reactor is50℃。

Example 4 and corresponding comparative examples 6, 7 used a pyrolysis gasoline C5-C9 cut, the reaction process conditions: fresh material airspeed of 2.0h^-1The operating pressure is 2.8MPa, the volume ratio of hydrogen to oil is 200:1, the dilution ratio of the product to the pure raw material is 3:1, and the inlet temperature of the reactor is 70 ℃.

The catalyst evaluation results are shown in Table 3.

TABLE 3 evaluation results of catalysts

In the embodiment 1, the particle diameters of the loaded Ni-Cu microemulsion and the loaded Pd microemulsion are respectively 61 nm and 50nm, and the maximum pore diameter of the small pore of the carrier is 28nm and the maximum pore diameter of the large pore is 280nm, which shows that the Ni-Cu and the Pd loaded by the microemulsion method mainly enter the large pore, so that the C1 catalyst in the embodiment 1 has excellent hydrogenation activity and stability, and the coking amount is less after 500 h; in the comparative example 1, the particle size of the Pd microemulsion is 20nm, which is located in the middle of the pore size of the small pores of the carrier, so that the Pd microemulsion cannot effectively enter the large pores, the Pd content of the alloy formed with Ni-Cu is reduced, part of Ni cannot be effectively reduced, and the green oil molecules cannot be effectively subjected to saturated hydrogenation, therefore, after 500 hours, the reaction effect of the catalyst in the comparative example is poorer than that in the embodiment.

In comparative example 2, the microemulsion supported Pd had a particle size of 400nm, which did not effectively lower the reduction temperature of Ni-Cu and further did not effectively saturate the green oil molecules, so the catalyst in comparative example 2 had a poorer reaction effect than the catalyst in example 2 after 500 hours.

In comparative example 3, W and Pd were simultaneously supported by the solution method, the geometric effect of W was strong, the electronic and geometric effects could not be effectively exerted, and the initial activity of the catalyst in comparative example was significantly inferior to that in example.

In comparative example 4, 3 components are simultaneously loaded, part of Pd is covered by Ni and Cu, so that the effect of Pd is weakened, the reduction temperature of Ni cannot be reduced, the saturated hydrogenation effect on olefin cannot be embodied, and the catalyst is seriously coked after 500 h.

In the comparative example 5, Pd and Cu are loaded firstly, and then loaded Ni covers part of Pd and Cu, so that Ni cannot be effectively reduced, and the catalyst is seriously coked after 500 hours.

In comparative example 6, Ni and Cu are loaded by a solution method, so that Ni-Cu is distributed too dispersedly and cannot enter macropores effectively, and colloid molecules cannot be hydrogenated effectively.

In the comparative example 7, a carrier with a single pore size distribution is adopted, the pore size is small, the microemulsion Ni-Cu and the microemulsion Pd particles cannot effectively enter pores and can not effectively hydrogenate colloid molecules, but the catalyst has low pore volume and limited colloid-containing capacity, so the coking amount after 500 hours is lower than that of the catalyst in the comparative example 6.

In the comparative example 8, when Ni-Cu is loaded by the microemulsion method, the particle size of the microemulsion is 30nm, so that a large amount of Ni-Cu enters small holes, Ni in large holes is less, and effective saturated hydrogenation can not be carried out on colloid molecules, therefore, after 500 hours, the reaction effect of the catalyst in the comparative example is poorer than that of the catalyst in the embodiment.

In comparative example 9, W was supported before Pd, the modification effect of W could not be effectively exerted, and the activity and selectivity of the catalyst in comparative example were poor.

In the comparative example 10, Pd is loaded firstly in the microemulsion method, and then the loaded Cu and Ni cover most of Pd, and most of Ni is not reduced in low-temperature reduction, so that the catalyst cannot perform a saturated hydrogenation function on larger molecular olefins, and the coking of the catalyst is most serious after 500 hours.

In the comparative example 11, Cu is loaded after the microemulsion method, Pd and Ni are loaded firstly, Cu is positioned at the outermost layer of the alloy, Cu is easier to reduce than Ni, but can not reduce all the alloy when the temperature is lower than 350 ℃, and coking is serious after 500 hours.

The present invention is capable of other embodiments, and various changes and modifications may be made by one skilled in the art without departing from the spirit and scope of the invention as defined in the appended claims.

Claims

1. A selective hydrogenation catalyst preparation method, the carrier of the catalyst is alumina or mainly alumina, and have bimodal pore distribution structure, the active component of catalyst at least contains Pd, W, Ni, Cu, characterized by that wherein Ni, Cu are supported by way of microemulsion, make Ni, Cu distribute in the macropore of the carrier mainly; w is loaded by a solution method; the Pd is loaded by adopting two modes of a solution method and a microemulsion method, wherein most of the Pd is loaded by adopting the solution method, and a small part of the Pd is loaded by adopting the microemulsion method.

2. The method for preparing a selective hydrogenation catalyst according to claim 1, wherein a major part of Pd is supported by a supersaturated impregnation method in a solution method, and a minor part of Pd is supported in a microemulsion method, so that the minor part of Pd is distributed in macropores of the carrier.

3. The preparation method of the selective hydrogenation catalyst according to claim 1, wherein the pore diameter of the carrier pores is 10-30 nm, the pore diameter of the macropores is 50-300 nm, and the particle size of the microemulsion is controlled to be larger than the pore diameter of the carrier pores and smaller than the pore diameter of the carrier macropores.

4. The method for preparing a selective hydrogenation catalyst according to claim 1, characterized in that the microemulsion mode loading process comprises: dissolving precursor salt in water, adding oil phase, surfactant and cosurfactant, and stirring to form microemulsion, wherein the oil phase is alkane or cycloalkane, the surfactant is ionic surfactant and/or nonionic surfactant, and the cosurfactant is organic alcohol.

5. The method for preparing a selective hydrogenation catalyst according to claim 4, wherein the microemulsion contains 1.5 to 2.5 weight ratio of the water phase to the oil phase, 0.2 to 0.7 weight ratio of the surfactant to the oil phase, and 1 to 1.2 weight ratio of the surfactant to the co-surfactant.

6. The process for preparing a selective hydrogenation catalyst according to claim 1, characterized in that the carrier Al₂O₃The crystal form is alpha, theta or a mixed crystal form thereof; the preferred catalyst support preferably contains at least 80% alumina.

7. The method for preparing a selective hydrogenation catalyst according to claim 1, wherein the step of loading Pd by the solution method is performed before or after the step of loading Ni and Cu by the microemulsion method, the step of loading W by the solution method is performed after the step of loading Pd by the solution method, and the step of loading Ni and Cu by the microemulsion method is performed before the step of loading Pd by the microemulsion method.

8. The method for preparing a selective hydrogenation catalyst according to claim 1, wherein the catalyst prepared by the preparation method is reduced at a reduction temperature of 150 to 200 ℃ before being put into a hydrogenation reaction.

9. The method of preparing a selective hydrogenation catalyst according to claim 1, characterized in that the catalyst preparation specifically comprises the steps of:

(1) preparing Pd into an active component impregnation liquid, adjusting the pH value to be 1.8-2.8, adding a carrier into the Pd active component impregnation liquid, performing impregnation and adsorption for 0.5-4 h, drying for 1-4 h at 100-120 ℃, and roasting for 2-6 h at 400-550 ℃ to obtain a semi-finished catalyst A;

(2) dissolving precursor salts of Ni and Cu in water, adding metered oil phase, surfactant and cosurfactant, fully stirring to form microemulsion, controlling the particle size of the microemulsion to be larger than the aperture of small holes of a carrier and smaller than the aperture of large holes of the carrier, adding the semi-finished catalyst A into the prepared microemulsion, soaking for 0.5-4 h, filtering out residual liquid, drying for 1-6 h at 80-120 ℃, and roasting for 2-8 h at 400-600 ℃ to obtain a semi-finished catalyst B;

(3) carrying out the loading of W by a solution saturation impregnation method, namely preparing a solution of W salt which is 80-110% of the saturated water absorption of the carrier, carrying W on the semi-finished product catalyst B, precipitating for 0.5-2 h, drying at 100-120 ℃ for 1-4 h, roasting at 400-550 ℃ for 4-6 h, and obtaining the semi-finished product catalyst C;

(4) dissolving Pd precursor salt in water, adding metered oil phase, surfactant and cosurfactant, fully stirring to form microemulsion, controlling the particle size of the microemulsion to be larger than the aperture of small holes of a carrier and smaller than the aperture of large holes of the carrier, adding a semi-finished catalyst C into the prepared microemulsion, soaking for 0.5-4 hours, filtering out residual liquid, drying for 1-6 hours at 80-120 ℃, and roasting for 2-8 hours at 400-600 ℃ to obtain the catalyst.