WO2024016576A1 - Selective hydrogenation catalyst for alkynes and preparation method therefor - Google Patents

Abstract

A selective hydrogenation catalyst for alkynes and a preparation method therefor. The catalyst contains at least the following active components: Pd and Ag. Based on the mass of a carrier being 100%, the content of Pd is 0.045-0.075%, and the content of Ag is 0.06-0.12%. The catalyst contains an organic cage, the organic cage is located on the outer surface of the catalyst, the size of the organic cage is 2.7-3.6 nm, Pd is loaded in the organic cage, and Ag is located in the middle or at the bottom of a Pd active center. When the catalyst of the present invention is applied to a selective hydrogenation process of a C2 fraction, the yield of butene can be reduced to 1/2 or below of a conventional catalyst, and the production of oxygen-containing compounds such as aldehydes is also significantly reduced.

Description

An alkyne selective hydrogenation catalyst and its preparation method Technical field

The invention relates to an alkyne selective hydrogenation catalyst and a preparation method thereof, and belongs to the technical field of catalyst preparation.

Background technique

Ethylene obtained by steam cracking of petroleum hydrocarbons (such as ethane, naphtha, diesel, hydrogenated tail oil, etc.) contains acetylene with a mass fraction of 0.2%-2.5%. When used in polymerization, acetylene in ethylene reduces the activity of the polymerization catalyst and affects the physical properties of the polymer, so it must be removed. At present, selective hydrogenation is commonly used in industry to remove acetylene from ethylene, and the catalysts used are mainly precious metal catalysts such as Pd, Pt, and Au. In order to ensure that the ethylene generated by acetylene hydrogenation and the original ethylene in the raw material do not continue to be hydrogenated to generate ethane, causing ethylene loss, the catalyst must have high hydrogenation selectivity to obtain better economic benefits.

The hydrogenation after carbon dioxide is based on the content of acetylene. Calculate the required hydrogen and add the hydrogenation materials. The molar ratio of hydrogen to acetylene generally does not exceed 2. It is precisely because of the lack of hydrogen that the hydrogenation dimerization reaction of acetylene easily occurs. , generating a carbon four fraction, which is further polymerized to form an oligomer with a wider molecular weight, commonly known as "green oil". Green oil is adsorbed on the surface of the catalyst and further forms coking, blocking the catalyst pores and preventing the reactants from diffusing to the active center surface of the catalyst, resulting in a decrease in catalyst activity.

Precious metal catalysts have high activity, but they are prone to generate green oil during use, causing coking and deactivation of the catalyst, affecting the stability and service life of the catalyst. CN200810119385.8 discloses a non-noble metal supported selective hydrogenation catalyst and its preparation method and application, including a carrier and a main active component and an auxiliary active component loaded on the carrier, wherein the main active component is Ni, and the co-active component is selected from at least one of Mo, La, Ag, Bi, Cu, Nd, Cs, Ce, Zn and Zr. The main active component and the co-active component are both amorphous. It exists in a state form, the average particle size is <10 nm, the carrier is a non-oxidizing porous material; and the catalyst is prepared by a micro-emulsification method.

CN200810114744.0 discloses an unsaturated hydrocarbon selective hydrogenation catalyst and its preparation method. This catalyst uses alumina as a carrier and palladium as an active component. By adding rare earth and alkaline earth metals and fluorine, the catalyst's resistance to impurities and coking is improved, but its catalyst selectivity is not ideal.

The catalysts prepared by the above methods all use catalysts with a single distribution of pore sizes. During the fixed bed reaction process, they are affected by internal diffusion and have poor selectivity. A carrier with bimodal pore distribution ensures high catalyst activity. At the same time, the existence of large pores can reduce the impact of internal diffusion and improve catalyst selectivity. CN101433842A discloses a hydrogenation catalyst, which is characterized in that the catalyst has a bimodal pore distribution. The maximum radius of the small pore part is 2-50nm, and the maximum radius of the large pore part is 100-500nm. Since the catalyst has a bimodal pore distribution, , which not only has good hydrogenation activity, but also has good selectivity and large ethylene increment.

In the carbon dioxide hydrogenation reaction, the formation of green oil and the coking of the catalyst are important factors affecting the service life of the catalyst. The activity, selectivity and service life of the catalyst constitute the overall performance of the catalyst. The methods listed above may provide better ways to improve the activity and selectivity of the catalyst, but they do not solve the problem of the catalyst being prone to coking, or the problem that the catalyst is prone to coking. It easily generates green oil and coking problems, but does not solve the problem of selectivity. Although a carrier with a macroporous structure can improve selectivity, larger molecules generated by polymerization and chain growth reactions can easily accumulate in the macropores of the carrier, causing coking and deactivation of the catalyst and affecting the service life of the catalyst.

In the carbon dioxide selective hydrogenation reaction, when Pd is the main active component, during the traditional impregnation catalyst preparation process, Pd is combined on the carrier in the form of Pd ²⁺ or [PdCl ₄ ] ^2- ions. During the activation process , Pd aggregates and becomes an active center. Since the aggregation of Pd during the activation process is a random process governed by dynamics, that is to say, the size of each active center is difficult to control in advance.

Previous research has found that the selective hydrogenation process of acetylene is as follows: first, an acetylene molecule is combined with a hydrogen atom to form a vinyl group, and then the vinyl group is combined with a hydrogen atom to form ethylene, or two vinyl groups are coupled to form Butadiene. Since butadiene can undergo a series of polymerization reactions to form green oil and then coke, inhibiting the formation of butadiene becomes the key to preventing coking of the carbon dioxide selective hydrogenation catalyst.

Obviously, if two vinyl groups are formed simultaneously on one catalyst active center, the probability of butadiene formation is greatly increased. Studies have also found that when the size of the active center is large, the yield of butadiene increases. To prevent the size of the active center from becoming large, there are generally two ways: one is to reduce the amount of active components, and the other is to expand the dispersion area of the active components. However, reducing the loading of active components may result in insufficient number of active centers, resulting in insufficient hydrogenation activity, inability to completely remove acetylene, unqualified hydrogenation products, and huge economic losses.

With the expansion of the active component loading area, part of the active center is not located close to the catalyst surface, resulting in poor catalyst selectivity and large ethylene loss during hydrogenation.

In order to prepare catalysts with narrow particle size distribution, some researchers have synthesized a series of organic cages with three-dimensional structures in recent years. These organic cages have fixed sizes and can be used to fix metals, thereby preparing catalysts with highly dispersed metal clusters. At present, these three-dimensional organic cages, after loading active components, are uniformly distributed in the solution or on the carrier, and are used for total hydrogenation or homogeneous hydrogenation. For selective hydrogenation, not only the size of the active center affects the reaction, but the distribution of active components in the catalyst also has a great impact on the reaction results. Catalysts with uniform distribution of active components are not suitable for Selective hydrogenation reaction.

There are currently many studies on noble metal single-atom catalysts in hydrogenation reactions, but for the hydrogenation of alkynes, there is still a considerable distance between the practical application of such catalysts. The reason is: in the active center of the hydrogenation reaction, two processes need to be completed. The first is the activation of the alkyne molecule, that is, the electron pair of the double bond of the alkyne molecule enters the empty orbit of the active center atom, and the active center atom The electron pairs are fed back to the anti-bonding orbital of the alkyne molecule, causing the double bond energy to decrease, the double bond to be activated, and broken; at the same time, the hydrogen molecule also needs the same process to activate the hydrogen into a hydrogen atom. For single-atom active centers, due to the limited physical size of a single atom, it is difficult to complete the two processes at the same time. Therefore, the reaction process is slow and difficult to meet the requirements of practical applications. Therefore, it is natural that the active neutrality needs to have a certain physical size. In fact, for palladium catalysts, since its stacked structure can absorb a large amount of hydrogen, the activation of hydrogen and the transfer of hydrogen atoms are important. It is completed within the stacking structure of palladium, so its activity is higher than that of active components that can only adsorb hydrogen on the surface.

Contents of the invention

In order to solve the above technical problems, the object of the present invention is to provide an acetylene selective hydrogenation catalyst and a preparation method, which are suitable for an acetylene selective hydrogenation process involving CO.

In order to achieve the above purpose, the present invention provides a selective hydrogenation catalyst, wherein the active components of the catalyst contain Pd and Ag. Based on the mass of the carrier being 100%, the content of Pd is 0.045-0.075%, and the content of Ag is 0.045-0.075%. 0.06-0.12%;

The catalyst contains an organic cage, which is located on the outer surface of the catalyst. The size of the organic cage is 2.7-3.6 nm. The Pd is loaded in the organic cage, and Ag is located in the middle or bottom of the Pd active center.

The catalyst of the present invention synthesizes organic cages with a regular structure in situ on the outer surface of the carrier. The size of the cages is 2.7-3.6 nm, and active components are loaded in these organic cages. Limited by the size of the organic cage, the size of the active center is also uniform, which can not only meet the activity needs, but also does not have an overly large active center. The probability of adsorbing olefins and CO at the same time during acetylene hydrogenation is greatly reduced.

In the catalyst of the present invention, Ag can form an alloy with Pd to improve the selectivity of acetylene hydrogenation. Specifically, Ag has two functions: one is that silver atoms separate palladium atoms and increase the spatial distance between adsorbed acetylene molecules. The distance between the corresponding reaction intermediates after hydrogenation of acetylene is larger, which prevents them from forming strongly adsorbed species of acetylene and makes it difficult for intermediate-vinyl coupling to occur, thus reducing the formation of green oil. This is called geometry. The second effect is that the S electrons in the outer layer of silver enter the empty orbit of palladium and reduce the adsorption of palladium on ethylene, which is called electron effect.

If the reaction material contains CO, due to its competitive adsorption relationship with acetylene, it can reduce the probability of strong adsorption of acetylene and play the above-mentioned geometric role. Therefore, Ag can not be exposed to the outer surface of the catalyst, but it will improve the selection of the catalyst. Physically, the electronic role of silver is still needed, so silver can be present inside or at the bottom of the active center of the catalyst.

According to a specific embodiment of the present invention, preferably, the specific surface area of the catalyst is 15-30 m ² /g.

According to a specific embodiment of the present invention, preferably, the carrier of the catalyst is alumina or mainly alumina.

According to the specific embodiment of the present invention, preferably, the crystal form of the alumina in the carrier can be θ, α crystal form or a mixed crystal form thereof; the alumina in the catalyst carrier accounts for more than 80%.

According to a specific embodiment of the present invention, preferably, the support also contains other metal oxides, such as magnesium oxide and/or titanium oxide.

The invention also provides a preparation method for the above catalyst, which mainly includes the following processes:

(1) A polar polymer is formed in the carrier, which occupies 80-95% of the pore volume of the carrier;

(2) In-situ synthesis of organic cages in the remaining outer pores of the carrier;

(3) Load the palladium active component in the organic cage, dry and then bake; decompose the polar polymer formed in step (1);

(4) Loading the active component silver;

(5) Load palladium active component in the organic cage.

According to the specific embodiment of the present invention, preferably, the above preparation method includes the following specific steps:

(1) Mix the hydrophilic polymerizable monomer with the calcined carrier and polymerize it at a certain temperature to obtain the first semi-finished catalyst, where the volume of the polymer synthesized by the hydrophilic monomer is the carrier pore volume 80-95% (preferably 85-95%);

(2) Mix tris(4-formylphenyl)amine and haloacetic acid, dissolve it in an alkyl halide, then mix it with the first semi-finished catalyst, stir and add dropwise a mixed solution of an aromatic diamine compound and an alkyl halide, and mix the mixture Leave to stand until the reaction is complete, pour out the residual liquid, wash with alcohol and deionized water respectively, and dry to obtain the second semi-finished catalyst;

Among them, the molar ratio of aromatic diamine compounds to tris(4-formylphenyl)amine is 1.2-2.5:1, and the mass ratio of tris(4-formylphenyl)amine to haloacetic acid is 2000-6000: 1;

(3) Dissolve the organic palladium salt in the organic solvent to obtain the first solution of the palladium precursor;

Immerse the second semi-finished catalyst in the alcohol solution, drop the first solution of the palladium precursor into the mixture of the second semi-finished catalyst and alcohol while stirring, then add the reducing agent dropwise, heat and stir until the surface of the second semi-finished catalyst no longer changes color. , pour off the solution, wash with deionized water, dry, and roast at a temperature where the polymer formed in step (1) can decompose, to obtain a third semi-finished catalyst;

(4) Dissolve the soluble silver salt in deionized water or an organic solvent to obtain a silver-containing impregnation solution. Immerse the third semi-finished catalyst into the silver-containing impregnation solution. After all is absorbed, let it stand and add dropwise for reduction. The agent is used to reduce the silver, the solution is poured out, washed with deionized water, and dried to obtain the fourth semi-finished catalyst;

(5) Dissolve the organic palladium salt in the organic solvent to obtain a second solution of the palladium precursor, immerse the fourth semi-finished catalyst in the alcohol solution, and drop the second solution of the palladium precursor into the mixture of the fourth semi-finished catalyst and alcohol, Stir simultaneously;

Add the reducing agent dropwise to the above solution, heat and stir, until the surface of the fourth semi-finished catalyst no longer changes color, pour off the solution, wash and dry to obtain the catalyst, or alternatively, without reduction, pour off the solution and wash with deionized water , dry and roast to obtain the catalyst.

According to the specific embodiment of the present invention, preferably, in the above preparation method, the mass ratio of the total mass of the organic palladium salt and tris(4-formylphenyl)amine described in step (3) and step (5) is 2-14 :1.

According to a specific embodiment of the present invention, preferably, in the above preparation method, step (4) is performed before step (3), and step (3) and step (5) are combined.

According to the specific embodiment of the present invention, in order to obtain a catalyst with uniform active center size, the present invention first prepares an organic cage, and then loads the active component palladium in the organic cage. The catalyst thus prepared has an active center of The scale is also in the range of 2.7-3.6nm, which can avoid the formation of two vinyl groups on one active center during the hydrogenation reaction, or the simultaneous adsorption of CO and ethylene.

If the synthesis process of the organic cage is carried out inside the carrier, the synthesized organic cage will be evenly distributed on the carrier, and the loaded catalyst active components will also be evenly distributed in all parts of the catalyst, and can only be used for full hydrogenation without considering selectivity. , or homogeneous hydrogenation without diffusion limitations, cannot be used for gas-phase selective hydrogenation. In order to ensure that the organic cage is located on the outer surface of the carrier, the present invention uses other media to occupy the pores inside the carrier in advance, so that the organic cage is synthesized in the pores close to the outer surface. In the catalyst obtained in this way, the active component Pd is distributed among the organic cages. Within the range, and the size of the active center is also within the appropriate range of 2.7-3.6nm, it can be suitable for gas-phase selective hydrogenation reactions, especially the selective hydrogenation process of carbon dioxide fractions.

According to specific embodiments of the present invention, the present invention does not limit the specific types of monomers used to synthesize organic cages, as long as the size of the synthesized organic cages is between 2.7-3.6 nm. Preferably, in step (1), the hydrophilic polymerizable monomer is a monomer containing a carbonyl group and/or a carboxyl group and capable of polymerization or condensation reaction, and more preferably includes lactic acid, acrylic acid or formaldehyde.

According to the specific embodiment of the present invention, the certain temperature in step (1) refers to the temperature at which the thermal condensation reaction or bulk polymerization of the monomer occurs, which varies depending on the monomer, and is generally 80-200°C.

According to specific embodiments of the present invention, the carrier in step (1) may be spherical, cylindrical, clover-shaped, four-leaf clover-shaped, etc.

According to a specific embodiment of the present invention, preferably, the decomposition temperature of the polymer formed from the hydrophilic polymerizable monomer is lower than 450°C, more preferably lower than 420°C.

According to a specific embodiment of the present invention, preferably, in step (2), the aromatic hydrocarbon diamines are tetraphenylenediamine or derivatives with substituents on its benzene ring, preferably p-tetraphenylenediamine. Amine or its derivative with a substituent on the benzene ring, the substituent is preferably a halogen or an alkyl group.

According to the specific embodiment of the present invention, preferably, haloacetic acid is a catalyst for the reaction of tris(4-formylphenyl)amine and aromatic diamine compounds. In step (2), the haloacetic acid is fluoroacetic acid. Acetic acid or chloroacetic acid, preferably trifluoroacetic acid or dichloroacetic acid.

According to the specific embodiment of the present invention, preferably, an alkyl halide is the solvent required for the reaction. In step (2), the alkyl halide includes an alkyl fluoride, an alkyl chloride or an alkyl bromide, and more preferably a methyl halide or an alkyl halide. Instead of ethane, dichloroethane or chloroform is more preferred.

According to specific embodiments of the present invention, preferably, in step (3) and step (5), the organic palladium salt includes palladium acetate or palladium acetylacetonate;

When the organic palladium salt is palladium acetylacetonate, the organic solvent is chloroform; when the organic palladium salt is palladium acetate, the organic solvent is one of chloroform, methylene chloride and glacial acetic acid. one or a combination of two or more.

According to a specific embodiment of the present invention, preferably, in step (3) and step (5), the alcohol includes ethanol or methanol, more preferably ethanol.

According to the specific embodiment of the present invention, preferably, in step (3), step (4) and step (5), the reducing agent is a reducing compound, more preferably methanol, formaldehyde, formic acid, ethanol, acetaldehyde , one or a combination of two or more of hydrazine hydrate.

According to a specific embodiment of the present invention, preferably, in step (4), the soluble silver salt is a silver salt soluble in water or an organic solvent, more preferably a silver nitrate soluble in water and/or a silver salt soluble in water. Silver acetylacetonate, etc. soluble in organic solvents. Ag is supported by a solution method, such as a saturated impregnation method.

According to a specific embodiment of the present invention, after loading Ag in step (4), Pd is loaded in step (5), and then can be calcined to form an oxidized state catalyst, or can be directly reduced to form a reduced state catalyst.

The invention also provides a carbon dioxide fraction selective hydrogenation process using crude hydrogen as the hydrogen source, which is carried out using the above catalyst.

The catalyst provided by the invention has the following characteristics: since palladium is loaded in an organic cage, limited by the physical size of the cage, the largest size of the active center composed of palladium is the size of the cage, reducing the activity with an aggregation size greater than 3.0 nm. center. This size meets the activity requirements for acetylene selectivity, but the probability of forming two vinyl groups at the same time in an active center or the simultaneous adsorption of CO and olefins is greatly reduced, reducing the probability of hydroformylation reaction and delaying catalyst deactivation. rate, the yield of butene can be reduced to less than 1/2 of that of traditional catalysts, and the production of oxygenated compounds such as aldehydes is also significantly reduced. Moreover, the organic cage is located on the outer surface of the catalyst, which avoids the impact of internal diffusion limitation on the catalytic reaction, and the catalyst has good selectivity. The use of the catalyst of the present invention can reduce the production of carbon four by-products, and hydrogenation of the carbonyl group of oxygen-containing compounds reduces the production of macromolecular oxygen-containing compounds.

Since the by-products are greatly reduced, the catalyst prepared by this method does not even need to be regenerated. Even if it is regenerated, the catalyst can be regenerated below 450°C, thereby not destroying the organic cage structure, ensuring good performance in the hydrogenation process, and greatly extending the catalyst life.

Description of drawings

Figure 1 shows the pore size of the organic cage synthesized in Example 1 measured by the BET method.

Detailed ways

In order to have a clearer understanding of the technical features, purposes and beneficial effects of the present invention, the technical solutions of the present invention are described in detail below, but this should not be understood as limiting the implementable scope of the present invention.

The following characterization methods are used in the preparation process of the catalyst of the present invention: BET measuring instrument, manufactured by Mack Company in the United States, measures the specific surface area and pore size distribution. The contents of Pd and Ag in the catalyst were measured on the A240FS atomic absorption spectrometer.

Agilent 7890A gas chromatograph measured hydrogen, acetylene content and butene content at the reactor outlet and inlet.

The weight of the catalyst was measured using a 0.1 mg electronic balance.

Ingredients: Tris(4-formylphenyl)amine, dichloroacetic acid, dichloroethane, diphenyldiamine, hydrazine hydrate, ethanol, methanol, acetic acid, formic acid, formaldehyde, lactic acid, acrylic acid, palladium acetate, palladium acetylacetonate , silver nitrate, analytical grade, Shanghai Sinopharm Group Company; alumina, Shandong Aluminum Group Company.

Example 1

This embodiment provides a catalyst, wherein:

Catalyst carrier: Commercially available spherical alumina carrier is used, with a diameter of 4mm. After roasting at 1080°C for 4 hours, the pore volume was 0.55m ³ /g and the specific surface area was 30m ² /g. Weigh 100g of the carrier.

Catalyst preparation:

(1) Weigh 65.31g of lactic acid and mix it with 100g of the roasted carrier, and keep at a constant temperature of 160°C for 10 hours to obtain semi-finished catalyst A;

(2) Mix 22.79 mg of tris(4-formylphenyl)amine with 0.00379 mg of dichloroacetic acid, dissolve in 60 ml of dichloroethane, then mix with semi-finished catalyst A1, stir and dropwise add 27.54 tetraphenylenediamine mg and 10 ml of dichloroethane, let the mixture stand at room temperature for 200 hours, pour out the residual liquid, wash with ethanol and deionized water respectively, and dry to obtain semi-finished catalyst B;

(3) Dissolve 38 mg of palladium acetate in 50 mL of glacial acetic acid. When the palladium acetate is completely dissolved, a palladium acetate solution is obtained. Immerse the semi-finished catalyst B into 50 mL of ethanol solution. Add the palladium acetate solution dropwise to the mixture of semi-finished catalyst B and ethanol. While stirring, add 20ml of about 40% formaldehyde solution dropwise to the above mixture, stir at 70°C for 1 hour, pour off the solution, wash with deionized water, dry at 120°C, and roast at 260°C for 8 hours to obtain a semi-finished product Catalyst C.

(4) Weigh 0.11g of silver nitrate, dissolve it into 52.3g of deionized water, immerse the semi-finished catalyst C into the prepared silver nitrate solution, wait until the solution is completely absorbed, let it stand for 4 hours, and then hydrate 5ml of 5% The hydrazine solution was added dropwise to the above solution, stirred at room temperature for 1 hour, the solution was poured off, washed with deionized water, and dried at 120°C to obtain semi-finished catalyst D.

(5) Dissolve 56.96 mg of palladium acetate in 50 mL of glacial acetic acid. Wait until the palladium acetate is completely dissolved to obtain a palladium acetate solution. Immerse the semi-finished catalyst D into 50 mL of ethanol solution. Add the palladium acetate solution dropwise to the mixture of semi-finished catalyst D and ethanol. While stirring, add 20 ml of about 40% formaldehyde solution dropwise to the above mixture, stir at 70°C for 1 hour, pour off the solution, wash with deionized water, and dry at 120°C to obtain the required catalyst.

The pore size results of the organic cage synthesized in Example 1 measured by the BET method are shown in Figure 1. As can be seen from Figure 1, the maximum pore diameter is 3.53nm and the minimum pore diameter is 2.91nm.

Atomic absorption spectrometry determined that in the catalyst prepared in Example 1, the Pd content was 0.045% and the Ag content was 0.07%.

Comparative example 1

This comparative example provides a catalyst in which:

Catalyst carrier: The carrier used in Example 1 was used.

Catalyst preparation: The preparation process conditions are the same as those in Example 1, except that silver is not supported;

(1) Weigh 65.30g of lactic acid and mix with 100g of roasted carrier, and keep at a constant temperature of 160°C for 10 hours to obtain semi-finished catalyst A1;

(2) Mix 22.79 mg of tris(4-formylphenyl)amine with 0.00379 mg of dichloroacetic acid, dissolve in 60 ml of dichloroethane, then mix with semi-finished catalyst A1, stir and dropwise add 27.54 tetraphenylenediamine mg and 10 ml of dichloroethane, let the mixture stand at room temperature for 200 hours, pour out the residual liquid, wash with ethanol and deionized water respectively, and dry to obtain semi-finished catalyst B1;

(3) Dissolve 38 mg of palladium acetate in 50 mL of glacial acetic acid. After the palladium acetate is completely dissolved to obtain a palladium acetate solution, immerse the semi-finished catalyst B1 in 50 mL of ethanol solution, and add the palladium acetate solution dropwise to the mixture of semi-finished catalyst B1 and ethanol. While stirring, add 20ml of about 40% formaldehyde solution dropwise to the above mixture, stir at 70°C for 1 hour, pour off the solution, wash with deionized water, dry at 120°C, and roast at 260°C for 8 hours to obtain a semi-finished product Catalyst C1.

(4) Dissolve 56.96 mg of palladium acetate in 50 mL of glacial acetic acid. Wait until the palladium acetate is completely dissolved to obtain a palladium acetate solution. Immerse the semi-finished catalyst C1 into 50 mL of ethanol solution. Add the palladium acetate solution dropwise to the mixture of semi-finished catalyst C1 and ethanol. While stirring, add 20 ml of about 40% formaldehyde solution dropwise to the above mixture, stir at 70°C for 1 hour, pour off the solution, wash with deionized water, and dry at 120°C to obtain the required catalyst.

The Pd content in the catalyst prepared in Comparative Example 1 was determined by atomic absorption spectrometry to be 0.045%.

Example 2

This embodiment provides a catalyst, wherein:

Carrier: Commercially available spherical alumina carrier is used, with a diameter of 3mm. After roasting at 1150°C for 4 hours, the water absorption pore volume was 0.65m ³ /g, and the specific surface area was 15.07m ² /g. Weigh 100g of the carrier.

Catalyst preparation:

(1) Weigh 73.7g of lactic acid and mix it with 100g of the roasted carrier, and keep at a constant temperature of 200°C for 10 hours to obtain semi-finished catalyst E;

(2) Mix 3.57 mg of tris(4-formylphenyl)amine with 0.0017 mg of dichloroacetic acid, dissolve in 60 ml of dichloroethane, then mix with semi-finished catalyst E, stir and dropwise add tetraphenyldiamine 8.89 mg and 10 ml of trichloroethane, let the mixture stand at room temperature for 200 hours, pour out the residual liquid, wash with ethanol and deionized water respectively, and dry to obtain semi-finished catalyst F;

(3) Dissolve 28.6 mg of palladium acetylacetonate in 50 mL of chloroform. Wait until the palladium acetylacetonate is completely dissolved to obtain a palladium acetylacetonate solution. Dip the semi-finished catalyst F into 50 mL of ethanol solution, and add the palladium acetylacetonate solution dropwise to the semi-finished catalyst. In the mixture of F and ethanol, stir simultaneously, then add 20ml of about 40% formaldehyde solution dropwise into the above mixture, stir at 70°C for 1 hour, pour off the solution, wash with deionized water, dry at 120°C, and dry at 300 °C for 8 hours to obtain semi-finished catalyst G.

(4) Weigh 0.094g of silver nitrate and dissolve it into 65g of deionized water. Immerse the semi-finished catalyst G into the prepared silver nitrate solution. After the solution is completely absorbed, let it stand for 4 hours. Then add 5ml of hydrazine hydrate with a concentration of 5%. The solution was added dropwise to the above solution, stirred at room temperature for 1 hour, the solution was poured off, washed with deionized water, and dried at 120°C to obtain the required catalyst. Semi-finished catalyst H was obtained.

(5) Dissolve 114.58 mg of palladium acetylacetonate in 50 mL of chloroform. When the palladium acetylacetonate is completely dissolved, immerse the semi-finished catalyst H in 50 mL of ethanol solution, and add the palladium acetylacetonate solution dropwise to the mixture of semi-finished catalyst H and ethanol. , while stirring, then add 20 ml of about 40% formaldehyde solution dropwise to the above mixture, stir at 70°C for 1 hour, pour off the solution, wash with deionized water, and dry at 120°C to obtain the required catalyst.

Atomic absorption spectrometry determined that in the catalyst prepared in Example 2, the Pd content was 0.05% and the Ag content was 0.06%.

Comparative example 2

This comparative example provides a catalyst in which:

Carrier: The same carrier as in Example 2 was used.

Catalyst preparation: The preparation conditions are the same as Example 2, except that all palladium is supported in step (3);

(1) Weigh 73.7g of lactic acid and mix it with 100g of the roasted carrier, and keep at a constant temperature of 200°C for 10 hours to obtain the semi-finished catalyst E1;

(2) Mix 3.57 mg of tris(4-formylphenyl)amine with 0.0017 mg of dichloroacetic acid, dissolve in 60 ml of dichloroethane, then mix with semi-finished catalyst E, stir and dropwise add tetraphenyldiamine 8.89 mg and 10 ml of trichloroethane, let the mixture stand at room temperature for 200 hours, pour out the residual liquid, wash with ethanol and deionized water respectively, and dry to obtain semi-finished catalyst F1;

(3) Dissolve 143.18 mg of palladium acetylacetonate in 50 mL of chloroform. Wait until the palladium acetylacetonate is completely dissolved to obtain a palladium acetylacetonate solution. Immerse the semi-finished catalyst F1 into 50 mL of ethanol solution, and add the palladium acetylacetonate solution dropwise to the semi-finished catalyst. In the mixture of F1 and ethanol, stir simultaneously, then add 20ml of about 40% formaldehyde solution dropwise into the above mixture, stir at 70°C for 1 hour, pour off the solution, wash with deionized water, dry at 120°C, and dry at 300°C °C for 8 hours to obtain a semi-finished catalyst G1.

(4) Weigh 0.094g of silver nitrate, dissolve it into 65g of deionized water, immerse the semi-finished catalyst G1 into the prepared silver nitrate solution, wait until the solution is completely absorbed, let it stand for 4 hours, and then add 5ml of hydrazine hydrate with a concentration of 5% The solution was added dropwise to the above solution, stirred at room temperature for 1 hour, decanted, washed with deionized water, and dried at 120°C to obtain the required catalyst.

Atomic absorption spectrometry determined that in the catalyst prepared in Comparative Example 2, the Pd content was 0.05% and the Ag content was 0.06%.

Example 3

This embodiment provides a catalyst, wherein:

Carrier: A commercially available spherical alumina-titanium oxide carrier is used, with a titanium oxide content of 20% and a diameter of 4mm. After roasting at 1105°C for 4 hours, the pore volume was 0.50m ³ /g and the specific surface area was 25.14m ² /g. Weigh 100g of the carrier.

Catalyst preparation:

(1) Weigh 18.9g acrylic acid, 26g water, 0.01g potassium hypophosphite monohydrate, 0.023g copper acetate monohydrate, 0.16ml 35% hydrogen peroxide as initiator, mix evenly, add 100g roasted carrier, wait After all the solution is absorbed, transfer it to a reflux bottle, heat to 80°C with stirring, and keep the temperature constant for 1 hour to obtain semi-finished catalyst I;

(2) Mix 16.25 mg of tris(4-formylphenyl)amine with 0.00325 mg of trichloroacetic acid, dissolve in 50 ml of dichloroethane, then mix with semi-finished catalyst I, stir and dropwise add 33.15 tetraphenylenediamine mg and 10 ml of trichloroethane, let the mixture stand at room temperature for 150 hours, pour out the residual liquid, wash with ethanol and deionized water respectively, and dry to obtain semi-finished catalyst J;

(3) Dissolve 29.13 mg of palladium acetylacetonate in 50 ml of chloroform. Wait until the palladium acetylacetonate is completely dissolved to obtain a palladium acetylacetonate solution. Dip the semi-finished catalyst J into 50 ml of ethanol solution, and add the palladium acetylacetonate solution dropwise to the semi-finished catalyst. J and ethanol mixture, while stirring, then add 10ml of about 50% formic acid solution dropwise to the above mixture, heat and stir at 70°C for 2 hours, pour off the solution, wash with deionized water, dry at 120°C, and dry at 400°C ℃ for 2 hours to obtain semi-finished catalyst K.

(4) Dissolve 0.16g of silver nitrate into 45g of deionized water, immerse the semi-finished catalyst K into the prepared silver nitrate solution. After the solution is completely absorbed, let it stand for 4 hours, then add 5ml of 10% hydrazine hydrate solution dropwise to the above solution. , stir at room temperature for 1 hour, pour off the solution, wash with deionized water, and dry at 120°C to obtain semi-finished catalyst M.

(5) Dissolve 156.84 mg of palladium acetylacetonate in 50 ml of chloroform. When the palladium acetylacetonate is completely dissolved, immerse the semi-finished catalyst M in 50 ml of ethanol solution. Add the prepared palladium acetylacetonate solution dropwise to the semi-finished catalyst M and ethanol. into the mixture while stirring, then add 10ml of about 50% formic acid solution dropwise into the above mixture, heat and stir at 70°C for 2 hours, pour off the solution, wash with deionized water, dry at 120°C, and roast at 400°C for 2 hours hours to obtain the desired catalyst.

Atomic absorption spectrometry determined that in the catalyst prepared in Example 3, the Pd content was 0.065% and the Ag content was 0.1%.

Comparative example 3

This comparative example provides a catalyst in which:

Carrier: The same carrier as in Example 3 was used.

Catalyst preparation: The catalyst preparation conditions are the same as those in Example 3, except that the tris(4-formylphenyl)amine in Comparative Example 3 is 4 times higher than that in Example 3;

(1) Weigh 18.9g acrylic acid, 26g water, 0.01g potassium hypophosphite monohydrate, 0.023g copper acetate monohydrate, 0.16ml 35% hydrogen peroxide as initiator, mix evenly, add 100g roasted carrier, wait After all the solution is absorbed, transfer it to a reflux bottle, heat to 80°C with stirring, and keep the temperature constant for 1 hour to obtain semi-finished catalyst I1;

(2) Mix 65 mg of tris(4-formylphenyl)amine with 0.00325 mg of trichloroacetic acid, dissolve in 50 ml of dichloroethane, then mix with semi-finished catalyst I1, stir and dropwise add 33.15 mg of tetraphenyldiamine Mixed solution with 10 ml of trichloroethane, let the mixture stand at room temperature for 150 hours, pour out the residual liquid, wash with ethanol and deionized water respectively, and dry to obtain semi-finished catalyst J1;

(3) Dissolve 29.13 mg of palladium acetylacetonate in 50 ml of chloroform. Wait until the palladium acetylacetonate is completely dissolved to obtain a palladium acetylacetonate solution. Dip the semi-finished catalyst J1 into 50 ml of ethanol solution, and add the palladium acetylacetonate solution dropwise to the semi-finished catalyst. In the mixture of J1 and ethanol, stir simultaneously, then add 10ml of about 50% formic acid solution dropwise into the above mixture, heat and stir at 70°C for 2 hours, pour off the solution, wash with deionized water, dry at 120°C, and dry at 400°C ℃ and calcined for 2 hours to obtain semi-finished catalyst K1.

(4) Dissolve 0.16g of silver nitrate into 45g of deionized water, immerse the semi-finished catalyst K1 into the prepared silver nitrate solution, wait until the solution is completely absorbed, let it stand for 4 hours, add 5ml of 10% hydrazine hydrate solution dropwise to the above solution, stir at room temperature for 1 hour, pour off the solution, wash with deionized water, and dry at 120°C to obtain semi-finished catalyst M1.

(5) Dissolve 156.84 mg of palladium acetylacetonate in 50 ml of chloroform. When the palladium acetylacetonate is completely dissolved, immerse the semi-finished catalyst M1 in 50 ml of ethanol solution. Add the prepared palladium acetylacetonate solution dropwise to the semi-finished catalyst M1 and ethanol. into the mixture while stirring, then add 10ml of about 50% formic acid solution dropwise into the above mixture, heat and stir at 70°C for 2 hours, pour off the solution, wash with deionized water, dry at 120°C, and roast at 400°C for 2 hours hours to obtain the desired catalyst.

Atomic absorption spectrometry determined that in the catalyst prepared in Comparative Example 3, the Pd content was 0.065% and the Ag content was 0.1%.

Example 4

This embodiment provides a catalyst, wherein:

Carrier: Commercially available tooth ball type alumina-magnesium oxide carrier is used, with a magnesium oxide content of 5% and a diameter of 3mm. After roasting at 1135°C for 4 hours, the pore volume was 0.55m ³ /g and the specific surface area was 22.39m ² /g. Weigh 100g of the carrier.

Catalyst preparation:

(1) Weigh 58.43g of lactic acid and mix with 100g of roasted carrier, add and keep at a constant temperature of 190°C for 2 hours to obtain semi-finished catalyst N;

(2) Mix 10.7 mg of tris(4-formylphenyl)amine with 0.0018 mg of trifluoroacetic acid, dissolve in 50 ml of dichloroethane, then mix with semi-finished catalyst N, stir and dropwise add 14.9 tetraphenyldiamine mg and 10 ml of dichloroethane, let the mixture stand at room temperature for 180 hours, pour out the residual liquid, wash with ethanol and deionized water respectively, and dry to obtain semi-finished catalyst O;

(3) Dissolve 94.95 mg of palladium acetate in 50 ml of chloroform. Wait until the palladium acetate is completely dissolved and set aside. Immerse the semi-finished catalyst O into 50 ml of ethanol solution, add the prepared palladium acetate solution dropwise to the mixture of semi-finished catalyst O and ethanol while stirring, and then add 20 ml of more than 80% methanol solution dropwise into the above mixture, at 80°C Stir for 1 hour, pour off the solution, wash with deionized water, dry at 120°C, and bake at 420°C for 1 hour to obtain semi-finished catalyst P.

(4) Dissolve 0.189g of silver nitrate into 53g of deionized water, immerse the semi-finished catalyst P into the prepared silver nitrate solution. After the solution is completely absorbed, let it stand for 4 hours, and then add 5 ml of hydrazine hydrate solution with a concentration of 5%. Add to the above solution, stir at room temperature for 1 hour, pour off the solution, wash with deionized water, and dry at 120°C to obtain semi-finished catalyst Q.

(5) Dissolve 63.31 mg of palladium acetate in 50 ml of chloroform. Wait until the palladium acetate is completely dissolved and set aside. Immerse the semi-finished catalyst Q into 50 ml of ethanol solution, add the prepared palladium acetate solution dropwise to the mixture of semi-finished catalyst Q and ethanol while stirring, and then add 20 ml of more than 80% methanol solution dropwise into the above mixture at 80°C. Stir for 1 hour, pour off the solution, wash with deionized water, dry at 120°C, and bake at 400°C for 1 hour to obtain the required catalyst.

Atomic absorption spectrometry determined that in the catalyst prepared in Example 4, the Pd content was 0.075% and the Ag content was 0.12%.

Comparative example 4

This comparative example provides a catalyst in which:

Carrier: The catalyst carrier is the same as in Example 4.

Catalyst preparation: The difference between this comparative example and Example 4 is that there is no step (1).

(1) Mix 10.7 mg of tris(4-formylphenyl)amine and 0.0018 mg of trifluoroacetic acid, dissolve in 50 ml of dichloroethane, then mix with the carrier, stir and dropwise add 14.9 mg of tetraphenylenediamine and A mixed solution of 10 ml of dichloroethane, let the mixture stand at room temperature for 180 hours, pour out the residual liquid, wash with ethanol and deionized water respectively, and dry to obtain semi-finished catalyst O1;

(2) Dissolve 94.95 mg of palladium acetate in 50 ml of chloroform. Wait until the palladium acetate is completely dissolved and set aside. Immerse the semi-finished catalyst O1 into 50 ml of ethanol solution, add the prepared palladium acetate solution dropwise to the mixture of semi-finished catalyst O1 and ethanol, while stirring, then add 20 ml of more than 80% methanol solution dropwise into the above mixture, at 80°C Stir for 1 hour, pour off the solution, wash with deionized water, dry at 120°C, and bake at 420°C for 1 hour to obtain semi-finished catalyst P1.

(3) Dissolve 0.189g of silver nitrate into 53g of deionized water, immerse the semi-finished catalyst P1 into the prepared silver nitrate solution, wait until all the solution is absorbed, let it stand for 4 hours, and then add 5ml of hydrazine hydrate solution with a concentration of 5%. Add to the above solution, stir at room temperature for 1 hour, pour off the solution, wash with deionized water, and dry at 120°C to obtain semi-finished catalyst Q1.

(4) Dissolve 63.31 mg of palladium acetate in 50 ml of chloroform. Wait until the palladium acetate is completely dissolved and set aside. Immerse the semi-finished catalyst Q1 into 50 ml of ethanol solution, add the prepared palladium acetate solution dropwise to the mixture of semi-finished catalyst Q1 and ethanol while stirring, and then add 20 ml of more than 80% methanol solution dropwise into the above mixture, at 80°C Stir for 1 hour, pour off the solution, wash with deionized water, dry at 120°C, and bake at 400°C for 1 hour to obtain the required catalyst.

Atomic absorption spectrometry determined that in the catalyst prepared in Comparative Example 4, the Pd content was 0.075% and the Ag content was 0.12%.

Example 5

This embodiment provides a catalyst, wherein:

Carrier: A spherical alumina-magnesium oxide carrier is used, with a magnesium oxide content of 10% and a diameter of 3mm. After roasting at 1100°C for 4 hours, the pore volume was 0.53m ³ /g and the specific surface area was 28.68m ² /g. Weigh 100g of the carrier.

Catalyst preparation:

(1) Weigh 63.90g of lactic acid and mix with 100g of roasted carrier, add and keep at a constant temperature of 180°C for 2 hours to obtain semi-finished catalyst R;

(2) Mix 11.67 mg of tris(4-formylphenyl)amine with 0.0047 mg of dichloroacetic acid, dissolve it in 50 ml of dichloroethane, then mix it with the semi-finished catalyst R, stir and dropwise add tetraphenyldiamine 26.19 mg and 10 ml of dichloroethane, let the mixture stand at room temperature for 190 hours, pour out the residual liquid, wash with ethanol and deionized water respectively, and dry to obtain semi-finished catalyst S;

(3) Dissolve 100 mg of palladium acetylacetonate in 50 ml of benzene. Wait until the palladium acetylacetonate is completely dissolved and set aside. Immerse the semi-finished catalyst S into 50 ml of more than 80% methanol solution, add the prepared palladium acetylacetonate solution dropwise to the mixture of semi-finished catalyst S and methanol, while stirring, and then add 10 ml of about 40% formaldehyde solution dropwise to the above mixture. , stir at 50°C for 1 hour, pour off the solution, wash with deionized water, dry at 120°C, and bake at 380°C for 1 hour to obtain semi-finished catalyst T.

(4) Dissolve 0.141g of silver nitrate into 53g of deionized water, immerse the semi-finished catalyst T into the prepared silver nitrate solution, wait until the solution is completely absorbed, let it stand for 4 hours, and then add 20ml of about 50% formic acid solution dropwise to the above In the solution, stir at 50°C for 1 hour, pour off the solution, wash with deionized water, and dry at 120°C to obtain semi-finished catalyst U.

(5) Dissolve 100 mg of palladium acetylacetonate in 50 ml of benzene. Wait until the palladium acetylacetonate is completely dissolved and set aside. Immerse the semi-finished catalyst U into 50 ml of methanol solution, add the prepared palladium acetylacetonate solution dropwise to the mixture of semi-finished catalyst U and methanol while stirring, and then add 10 ml of about 40% formaldehyde solution dropwise into the above mixture, at 50 Stir for 1 hour at ℃, pour off the solution, wash with deionized water, dry at 120℃, and bake at 380℃ for 1 hour to obtain the desired catalyst.

The atomic absorption spectrometry method determined that in the catalyst prepared in Example 5, the Pd content was 0.07% and the Ag content was 0.09%.

Comparative example 5

This comparative example provides a catalyst, in which the catalyst carrier is the same as in Example 5, except that the catalyst is prepared using a traditional method.

(1) Weigh 116.67 mg of palladium chloride, dissolve it in 80 ml of deionized water, adjust the pH to 2.5, immerse 100 g of the roasted carrier in the solution, dry it at 120°C after 30 minutes, and roast it at 500°C to obtain the semi-finished catalyst T1;

(2) Weigh 142.16 mg of silver nitrate and dissolve it in 52.25 g of deionized water to obtain a silver nitrate solution. Dip the semi-finished catalyst T1 into the prepared silver nitrate solution. After the solution is completely absorbed, dry it at 100°C and roast it at 550°C. , to obtain the desired catalyst.

Atomic absorption spectrometry determined that in the catalyst prepared in Comparative Example 5, the Pd content was 0.07% and the Ag content was 0.09%.

Example 6

This embodiment provides a catalyst, wherein:

Carrier: A commercially available spherical carrier is used, with 95% alumina, 5% titanium oxide content, and a diameter of 3 mm. After roasting at 1090°C for 4 hours, the pore volume was 0.48m ³ /g and the specific surface area was 30.13m ² /g. Weigh 100g of the carrier.

Catalyst preparation:

(1) Weigh 57.14g of lactic acid and mix it with 100g of the roasted carrier, and keep at a constant temperature of 190°C for 1 hour to obtain the semi-finished catalyst V;

(2) Mix 8.13 mg of tris(4-formylphenyl)amine with 0.0023 mg of trifluoroacetic acid, dissolve it in 50 ml of dichloroethane, then mix it with the semi-finished catalyst V, stir and dropwise add 3-methyl tetrad A mixed solution of 15.46 mg of phenylenediamine and 10 ml of dichloroethane, let the mixture stand at room temperature for 100 hours, pour out the residual liquid, wash with ethanol and deionized water respectively, and dry to obtain semi-finished catalyst W;

(3) Weigh 173.23mg of silver nitrate, dissolve it into 48g of deionized water, immerse the semi-finished catalyst W into the prepared solution, wait until all the solution is absorbed, let it stand for 4 hours, and then add 50ml of more than 50% acetaldehyde solution dropwise into the above solution, stir at 60°C for 1 hour, pour off the solution, wash with deionized water, and dry at 120°C to obtain semi-finished catalyst Y.

(4) Dissolve 137.16 mg of palladium acetate in 50 ml of dichloroethane. When the palladium acetate is completely dissolved, the prepared solution is ready for use. Immerse the semi-finished catalyst Y in 50 ml of ethanol solution, add the prepared palladium acetate solution dropwise to the mixture of semi-finished catalyst Y and ethanol while stirring, and then add 30 ml of more than 50% acetaldehyde solution dropwise into the above mixture, at 60 Stir at 120°C for 1 hour, pour off the solution, wash with deionized water, and dry at 120°C to obtain the desired catalyst.

The atomic absorption spectrometry method determined that in the catalyst prepared in Example 6, the Pd content was 0.065% and the Ag content was 0.11%.

Comparative example 6

This comparative example provides a catalyst in which:

Carrier: Use the same carrier as Example 6. The difference from Example 6 is that phenylenediamine with the same mole number as 3-methyltetraphenylenediamine is used and prepared with tris(4-formylphenyl)amine. Organic cage.

Catalyst preparation:

(1) Weigh 57.14g of lactic acid and mix it with 100g of the roasted carrier, and keep at a constant temperature of 190°C for 1 hour to obtain the semi-finished catalyst V1;

(2) Mix 8.13 mg of tris(4-formylphenyl)amine with 0.0023 mg of trifluoroacetic acid, dissolve it in 50 ml of dichloroethane, then mix it with the semi-finished catalyst V1, stir and dropwise add 4.80 mg of phenylenediamine and A mixed solution of 10 ml of dichloroethane, let the mixture stand at room temperature for 100 hours, pour out the residual liquid, wash with ethanol and deionized water respectively, and dry to obtain semi-finished catalyst W1;

(3) Weigh 173.23mg of silver nitrate, dissolve it into 48g of deionized water, immerse the semi-finished catalyst W1 into the prepared solution, wait until all the solution is absorbed, let it stand for 4 hours, and then add 50ml of more than 50% acetaldehyde solution dropwise into the above solution, stir at 60°C for 1 hour, pour off the solution, wash with deionized water, and dry at 120°C to obtain semi-finished catalyst Y1.

(4) Dissolve 137.16 mg of palladium acetate in 50 ml of dichloroethane. When the palladium acetate is completely dissolved, the prepared solution is ready for use. Immerse the semi-finished catalyst Y1 into 50 ml of ethanol solution, and add the prepared palladium acetate solution dropwise to the semi-finished product. In the mixture of catalyst Y1 and ethanol, stir simultaneously, then add 30ml of more than 50% acetaldehyde solution dropwise into the above mixture, stir at 60°C for 1 hour, pour off the solution, wash with deionized water, and dry at 120°C. Obtain the desired catalyst.

Atomic absorption spectrometry determined that in the catalyst prepared in Comparative Example 6, the Pd content was 0.065% and the Ag content was 0.11%.

Example 7

This embodiment provides a catalyst, wherein:

Carrier: Commercially available spherical alumina carrier is used, with a diameter of 4mm. After roasting at 1135°C for 4 hours, the water absorption pore volume was 0.60m ³ /g, and the specific surface area was 21.75m ² /g. Weigh 100g of the carrier.

Catalyst preparation:

(1) Weigh 67.5g of lactic acid and mix with 100g of roasted carrier, add and keep at a constant temperature of 210°C for 2 hours to obtain semi-finished catalyst AA;

(2) Mix 17.14 mg of tris(4-formylphenyl)amine with 0.0057 mg of difluoroacetic acid, dissolve in 50 ml of dichloroethane, then mix with semi-finished catalyst AA, stir and drop 2-chlorotetraphenyl A mixed solution of 42.40 mg diamine and 10 ml dichloroethane, let the mixture stand at room temperature for 120 hours, pour out the residual liquid, wash with ethanol and deionized water respectively, and dry to obtain semi-finished catalyst BB;

(3) Weigh 51.53 mg of palladium acetate and dissolve it in 50 ml of dichloroethane. Wait until the palladium acetate is completely dissolved to obtain a palladium acetate solution.

Immerse the semi-finished catalyst BB in 50 ml of ethanol solution, add the prepared palladium acetate solution dropwise to the mixture of semi-finished catalyst BB and methanol while stirring, and then add 3 ml of hydrazine hydrate solution with a concentration of 5% dropwise into the above mixture. Stir at room temperature for 1 hour, pour off the solution, wash with deionized water, dry at 120°C, and bake at 300°C for 2 hours to obtain semi-finished catalyst CC.

(4) Weigh 0.23g of silver acetylacetonate, dissolve it into 60ml of toluene, immerse the semi-finished catalyst CC into the prepared silver acetylacetonate solution, wait until the solution is completely absorbed, let it stand for 4 hours, and then hydrate 3ml of 5% concentration of silver acetylacetonate. Add the hydrazine solution dropwise to the above solution, stir at room temperature for 1 hour, pour off the solution, wash with deionized water, and dry at 120°C to obtain the semi-finished catalyst DD.

(5) Weigh 73.47 mg of palladium acetate and dissolve it in 50 ml of dichloroethane. Wait until the palladium acetate is completely dissolved to obtain a palladium acetate solution.

Immerse the semi-finished catalyst DD into 50 ml of ethanol solution, add the prepared palladium acetate solution dropwise to the mixture of semi-finished catalyst DD and methanol while stirring, and then add 3 ml of hydrazine hydrate solution with a concentration of 5% dropwise into the above mixture. Stir at room temperature for 1 hour, pour off the solution, wash with deionized water, dry at 120°C, and bake at 300°C for 2 hours to obtain the desired catalyst.

Atomic absorption spectrometry determined that in the catalyst prepared in Example 7, the Pd content was 0.06% and the Ag content was 0.12%.

Comparative example 7

This comparative example provides a catalyst in which:

Carrier: The same carrier as in Example 7 was used.

Catalyst preparation: The preparation conditions are the same as Example 7, except that the calcination temperature in step (3) is 600°C.

(1) Weigh 67.5g of lactic acid and mix with 100g of roasted carrier, add and keep at a constant temperature of 210°C for 2 hours to obtain semi-finished catalyst AA1;

(2) Mix 17.14 mg of tris(4-formylphenyl)amine with 0.0057 mg of difluoroacetic acid, dissolve in 50 ml of dichloroethane, then mix with semi-finished catalyst AA1, stir and dropwise add 2-chlorotetrad A mixed solution of 42.40 mg phenylenediamine and 10 ml dichloroethane, let the mixture stand at room temperature for 120 hours, pour out the residual liquid, wash with ethanol and deionized water respectively, and dry to obtain semi-finished catalyst BB1;

(3) Weigh 51.53 mg of palladium acetate and dissolve it in 50 ml of dichloroethane. Wait until the palladium acetate is completely dissolved to obtain a palladium acetate solution.

Immerse the semi-finished catalyst BB1 in 50 ml of ethanol solution. Add the prepared palladium acetate solution dropwise to the mixture of semi-finished catalyst BB1 and methanol while stirring. Then add 3 ml of hydrazine hydrate solution with a concentration of 5% dropwise into the above mixture. Stir at room temperature for 1 hour, pour off the solution, wash with deionized water, dry at 120°C, and bake at 600°C for 2 hours to obtain semi-finished catalyst CC1.

(4) Weigh 0.23g of silver acetylacetonate and dissolve it in 60ml of toluene. Immerse the semi-finished catalyst CC1 into the prepared silver acetylacetonate solution. After the solution is completely absorbed, let it stand for 4 hours, and then hydrate 3ml of 5% silver acetylacetonate solution. The hydrazine solution was added dropwise to the above solution, stirred at room temperature for 1 hour, the solution was poured off, washed with deionized water, and dried at 120°C to obtain the semi-product catalyst DD1.

(5) Weigh 73.47 mg of palladium acetate and dissolve it in 50 ml of dichloroethane. Wait until the palladium acetate is completely dissolved to obtain a palladium acetate solution.

Immerse the semi-finished catalyst DD1 into 50 ml of ethanol solution, add the prepared palladium acetate solution dropwise to the mixture of semi-finished catalyst DD1 and methanol while stirring, and then add 3 ml of hydrazine hydrate solution with a concentration of 5% dropwise into the above mixture. Stir at room temperature for 1 hour, pour off the solution, wash with deionized water, dry at 120°C, and bake at 300°C for 2 hours to obtain the desired catalyst.

Atomic absorption spectrometry determined that in the catalyst prepared in Comparative Example 7, the Pd content was 0.06% and the Ag content was 0.12%.

Performance of catalysts used in carbon dioxide post-hydrogenation reactions

Evaluation method:

The loading volume of the catalyst in the fixed bed section reactor is 100 mL (record the weight), the filler is 50 mL, the reaction material space velocity is 4000/h, the operating pressure is 2.5 MPa, the hydrogen-to-yne ratio is 1.5, and the reactor inlet temperature is 75°C.

Catalyst reduction: hydrogen flow rate 10 liters/hour, constant temperature 130°C for 4 hours.

The calculation method of the evaluation results is shown in Table 1.

Table 1 Calculation method of evaluation results

The initial selectivity is the selectivity measured 24 hours after the reactor is fed.

The initial activity is the activity (acetylene conversion rate) measured 24 hours after the reactor is fed.

The reaction material composition is as follows:

Acetylene 0.9% (mol/mol), ethylene 82% (mol/mol), ethane 17% (mol/mol), CO 200ppm, carbon three content 0.5% (mol/mol).

Catalyst evaluation results are shown in Table 2.

Table 2 Catalyst evaluation results

It can be seen from the comparison of the catalyst evaluation results in Table 2:

Compared with Example 1, the selectivity in Comparative Example 1 is at least 5 percentage points lower due to the absence of loaded silver.

In Comparative Example 2, since all palladium is loaded first and silver is loaded later, part of the active sites on the surface of the active center is occupied by silver, and the ability to adsorb alkynes decreases. Compared with Example 2, the catalytic activity decreases significantly.

In Comparative Example 3, the amount of tris(4-formylphenyl)amine increased significantly, the number of organic cages formed in the early stage of synthesis increased, and the corresponding number of active centers was too many. The size of the palladium active center supported by a single organic cage became smaller, resulting in the catalyst Insufficient activity.

In Comparative Example 4, the polar polymer was not synthesized in the carrier in advance. The synthesis reaction of the organic cage was carried out at all parts inside the carrier. The active center for loading palladium was also located at all parts inside the carrier and was limited by the diffusion of reaction molecules. Its activity selectivity is worse than that of Example 4.

In Comparative Example 5, the catalyst was prepared by a traditional method. Since silver occupied part of the outer surface of the active center, the catalyst activity was reduced. The situation is similar to that of Comparative Example 2.

In Comparative Example 6, phenylenediamine was used instead of terphenylenediamine. The synthesized organic cage was significantly smaller, and the size of the active center was also smaller. In the carbon dihydrogenation reaction involving CO, the activity of the catalyst was insufficient.

In Comparative Example 7, during the roasting process in step (3), the temperature was higher than the decomposition temperature of the organic cage, causing the organic cage to disintegrate. When loading palladium in step (5), part of the palladium could not be loaded in the organic cage. Dispersed in other parts of the carrier, the catalyst activity is obviously low.

Under the condition that CO participates in the reaction, CO can be adsorbed on palladium atoms and form competitive adsorption with acetylene, which reduces the probability of forming multiple vinyl groups at the same active center at the same time, objectively reducing the amount of green oil produced and improving The role of selectivity. However, CO may still form strong adsorption and formylation reactions may occur. In order to reduce the formylation reaction, it is necessary to reduce the adsorption strength of CO on the active center. The electronic effect after the silver and palladium form an alloy can be used. That is, the S electrons of silver first enter the outer empty orbit of palladium. At this time, there is no need to expose silver. outside the active center. Silver does not occupy the position of the outer layer, so the activity of the catalyst is not significantly reduced. Compared with the traditional method, the catalyst of the present invention has a significantly reduced loading capacity of precious metal palladium, the production of green oil is also reduced, and the catalyst operation cycle is extended.

Claims (27)

1. An alkyne selective hydrogenation catalyst, wherein the active components of the catalyst contain Pd and Ag. Based on the mass of the carrier being 100%, the content of Pd is 0.045-0.075% and the content of Ag is 0.06-0.12%;

   The catalyst contains an organic cage, which is located on the outer surface of the catalyst. The size of the organic cage is 2.7-3.6 nm. The Pd is loaded in the organic cage, and Ag is located in the middle or bottom of the Pd active center.
2. The catalyst according to claim 1, wherein the specific surface area of the catalyst is 15-30 m ² /g.
3. The catalyst according to claim 1, wherein the carrier of the catalyst is alumina or mainly alumina.
4. The catalyst according to claim 3, wherein the crystal form of the alumina in the carrier is θ, α crystal form or a mixed crystal form thereof; the alumina in the catalyst carrier accounts for more than 80%.
5. The catalyst according to claim 3, wherein the carrier further contains magnesium oxide and/or titanium oxide.
6. The preparation method of the catalyst according to any one of claims 1-5, which includes the following steps:

   (1) Mix the hydrophilic polymerizable monomer with the calcined carrier and polymerize it at a certain temperature to obtain the first semi-finished catalyst, wherein the volume of the polymer synthesized by the hydrophilic polymerizable monomer is the carrier 80-95% of pore volume;

   (2) Mix tris(4-formylphenyl)amine and haloacetic acid, dissolve it in an alkyl halide, then mix it with the first semi-finished catalyst, stir and add dropwise a mixed solution of an aromatic diamine compound and an alkyl halide, and mix the mixture Leave to stand until the reaction is complete, pour out the residual liquid, wash with alcohol and deionized water respectively, and dry to obtain the second semi-finished catalyst;

   Among them, the molar ratio of aromatic diamine compounds to tris(4-formylphenyl)amine is 1.2-2.5:1, and the mass ratio of tris(4-formylphenyl)amine to haloacetic acid is 2000-6000: 1;

   (3) Dissolve the organic palladium salt in the organic solvent to obtain the first solution of the palladium precursor;

   Immerse the second semi-finished catalyst in the alcohol solution, drop the first solution of the palladium precursor into the mixture of the second semi-finished catalyst and alcohol while stirring, then add the reducing agent dropwise, heat and stir until the surface of the second semi-finished catalyst no longer changes color. , pour off the solution, wash with deionized water, dry, and roast at a temperature where the polymer formed in step (1) can decompose, to obtain a third semi-finished catalyst;

   (4) Dissolve the soluble silver salt in deionized water or an organic solvent to obtain a silver-containing impregnation solution. Immerse the third semi-finished catalyst into the silver-containing impregnation solution. After all is absorbed, let it stand and add dropwise for reduction. The agent is used to reduce the silver, the solution is poured out, washed with deionized water, and dried to obtain the fourth semi-finished catalyst;

   (5) Dissolve the organic palladium salt in the organic solvent to obtain a second solution of the palladium precursor, immerse the fourth semi-finished catalyst in the alcohol solution, and drop the second solution of the palladium precursor into the mixture of the fourth semi-finished catalyst and alcohol, Stir simultaneously;

   Add the reducing agent dropwise to the above solution, heat and stir, until the surface of the fourth semi-finished catalyst no longer changes color, pour off the solution, wash and dry to obtain the catalyst, or alternatively, without reduction, pour off the solution and wash with deionized water , dry and roast to obtain the catalyst.
7. The preparation method according to claim 6, wherein in step (1), the volume of the polymer synthesized from the hydrophilic polymerizable monomer is 85-95% of the pore volume of the carrier.
8. The preparation method according to claim 6, wherein the mass ratio of the total mass of palladium in the organic palladium salt and tris(4-formylphenyl)amine in steps (3) and (5) is 2-14 :1.
9. The preparation method according to claim 6, wherein in step (1), the hydrophilic polymerizable monomer is a monomer containing a carbonyl group and/or a carboxyl group and capable of polymerization or condensation reaction.
10. The preparation method according to claim 9, wherein in step (1), the hydrophilic polymerizable monomer includes lactic acid, acrylic acid or formaldehyde.
11. The preparation method according to claim 9, wherein the decomposition temperature of the polymer formed by the hydrophilic polymerizable monomer is lower than 450°C.
12. The preparation method according to claim 11, wherein the decomposition temperature of the polymer formed by the hydrophilic polymerizable monomer is lower than 420°C.
13. The preparation method according to claim 6, wherein in step (2), the aromatic hydrocarbon diamines are tetraphenylenediamine or derivatives with substituents on its benzene ring.
14. The preparation method according to claim 13, wherein in step (2), the aromatic hydrocarbon diamines are p-tetraphenylenediamine or derivatives with substituents on its benzene ring.
15. The preparation method according to claim 13, wherein the substituent is halogen or alkyl.
16. The preparation method according to claim 6, wherein in step (2), the haloacetic acid is fluoroacetic acid or chloroacetic acid.
17. The preparation method according to claim 16, wherein in step (2), the haloacetic acid is trifluoroacetic acid or dichloroacetic acid.
18. The preparation method according to claim 6, wherein in step (2), the alkyl halide includes an alkyl fluoride, an alkyl chloride or an alkyl bromide.
19. The preparation method according to claim 18, wherein in step (2), the alkyl halide is methyl halide or ethane halide.
20. The preparation method according to claim 19, wherein in step (2), the alkyl halide is dichloroethane or chloroform.
21. The preparation method according to claim 6, wherein in step (3) and step (5), the organic palladium salt includes palladium acetate or palladium acetylacetonate;

    When the organic palladium salt is palladium acetylacetonate, the organic solvent is chloroform; when the organic palladium salt is palladium acetate, the organic solvent is one of chloroform, methylene chloride and glacial acetic acid. one or a combination of two or more.
22. The preparation method according to claim 6, wherein in step (3) and step (5), the alcohol includes ethanol or methanol.
23. The preparation method according to claim 6, wherein in step (3), step (4) and step (5), the reducing agent is a reducing compound.
24. The preparation method according to claim 23, wherein in step (3), step (4) and step (5), the reducing agent is one of methanol, formaldehyde, formic acid, ethanol, acetaldehyde, and hydrazine hydrate. one or a combination of two or more.
25. The preparation method according to claim 6, wherein in step (4), the soluble silver salt is a silver salt soluble in water or an organic solvent.
26. The preparation method according to claim 25, wherein in step (4), the soluble silver salt is silver nitrate and/or silver acetylacetonate.
27. The preparation method according to claim 6, wherein step (4) is carried out before step (3), and step (3) and step (5) are combined.

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