WO2021110082A1 - Method for preparing monoolefin by means of hydrogenation of diolefin - Google Patents

Abstract

Disclosed is a method for preparing a monoolefin by means of the hydrogenation of a diolefin. The method comprises the step of reacting a raw material containing a diolefin with hydrogen in the presence of a catalyst, wherein the catalyst includes a carrier comprising a first carrier and a second carrier covering the outside surface of the first carrier, and a catalytic active component loaded on the second carrier, in which the first carrier has a porosity of ≤35%, the ratio of the thickness of the second carrier to the effective diameter of the first carrier is between 0.01-0.2, the pore distribution curve of the second carrier has two pore distribution peaks, the pore size corresponding to the peak value of a first pore distribution peak is in the range of 4-80 nm, and the pore size corresponding to the peak value of a second pore distribution peak is in the range of 100-8000 nm. The method has an improved conversion rate and selectivity for a hydrogenation reaction.

Description

Method for preparing monoolefin by hydrogenating diolefin

Cross-references to related applications

This application claims the priority of the patent application filed on December 3, 2019 with application number 201911230630.7 and titled "A method for hydrogenating diolefins to monoolefins", the content of which is incorporated herein by reference in its entirety. .

Technical field

The application relates to the technical field of olefin catalytic hydrogenation, in particular to a method for preparing monoolefins by hydrogenating diolefins.

Background technique

In the production of synthetic detergents and various surfactants, long-chain hydrocarbons are involved. For example, in the process of dehydrogenation to produce detergent raw materials-linear alkyl benzene, C ₁₀ -C ₁₅ long-chain alkanes are produced by dehydrogenation The monoolefin product contains a small amount of diolefins, and the presence of these diolefins will cause a large number of side reactions in the subsequent alkylation process, which reduces the yield and quality of alkylbenzene. The selective hydrogenation of diolefins is used to selectively hydrogenate the diolefins in the dehydrogenation products to generate monoolefins, which can effectively improve the quality of alkylbenzenes on the basis of increasing the yield of alkylbenzenes.

In _{the selective hydrogenation of C 10} -C ₁₅ diolefins, the performance of the catalyst is an important indicator of influence. There are many patents for catalysts for selective hydrogenation of diolefins that have been reported. Most of these catalysts are supported by porous activated alumina, with elements such as nickel, molybdenum, and palladium as the main catalytically active components.

US patents US4695560A, US4523048A, US4520214A, US4761509A and Chinese patent application CN1032157A disclose a selective hydrogenation method for diolefins used in C8-C20 alkane dehydrogenation products. This method uses a nickel- and sulfur-containing catalyst and does not contain precious metals. Because the catalyst in this method is nickel as the main catalyst element, in order to achieve a certain reaction activity, the reaction needs to be carried out at a higher temperature. At the same time, in order to obtain a certain selectivity, it is necessary to inject sulfur frequently to sulfide the catalyst, resulting in a complicated process flow of the method. , The operation is difficult, it is difficult to obtain high reaction activity and high selectivity at the same time, the investment cost of the device is high, and the material consumption is large.

Chinese patent application CN1236333A reports a preparation method and scope of use of a selective hydrogenation catalyst containing palladium and at least one element selected from tin and lead. The catalyst reported in this patent is based on alumina with a specific surface area of 5-200m ² /g and a pore volume of 0.3-0.95cm ³ /g as a carrier. The surface impregnation method is used to distribute at least 80% of the active element palladium around the particles. In the particle volume between 500μm in depth. The catalyst is suitable for selective hydrogenation of butadiene and other low-carbon hydrocarbons. Because the specific surface area and pore volume of the carrier used in the catalyst are relatively small, it is not suitable for _{the selective hydrogenation of C 10} -C ₁₅ long-chain diolefins.

In the selective hydrogenation reaction, C ₁₀ -C ₁₅ diolefins will enter the pores of the catalyst carrier during the reaction, and diffuse from the surface of the catalyst through the pores to the inside of the catalyst. The C ₁₀ -C ₁₅ monoolefins produced by the reaction are then removed from the catalyst. The inside diffuses to the surface of the catalyst through the pores. Due to the _{long carbon chain of the C 10} -C ₁₅ diolefin, the mass transfer resistance in the pores of the catalyst carrier is large. The internal diffusion distance of the traditional catalyst is long, the residence time is long, and the depth is very easy to occur. The side reaction reduces the conversion rate and selectivity of the hydrogenation reaction.

Summary of the invention

The purpose of this application is to provide a method for preparing monoolefins by hydrogenation of diolefins, which improves the conversion rate and selectivity of the hydrogenation reaction by adopting a catalyst with a double-layer support structure.

In order to achieve the above objective, the present application provides a method for hydrogenating diolefins to prepare monoolefins, which includes the step of reacting a raw material containing diolefins with hydrogen in the presence of a catalyst, wherein the catalyst includes a support, and the support includes a first The carrier, the second carrier coated on the outer surface of the first carrier, and the catalytically active component supported on the second carrier, wherein the porosity of the first carrier is ≤ 35%, and the second carrier The ratio of the thickness to the effective diameter of the first carrier is between 0.01-0.2, and the pore distribution curve of the second carrier has two pore distribution peaks, wherein the peak of the first pore distribution peak corresponds to the pore diameter of 4-80 nm The pore diameter corresponding to the peak of the second pore distribution peak is in the range of 100-8000 nm.

The catalyst used in the present application is formed by selecting different substances to form a catalyst carrier which contains a first carrier and a second carrier coated on the outer surface of the first carrier with different internal and external properties. The catalytic reaction active centers are distributed on the second carrier in the outer layer. , Which greatly shortens the diffusion distance of reactants and products in the catalyst. In addition, by adjusting the pore structure of the second carrier, two different types of pores with different pore diameters are provided. The first type of pores provides the high specific surface area and active centers required for the reaction, thereby improving the reaction activity of the catalyst; The second-type pores are used as diffusion channels for reactants and products, which greatly improves the diffusion process of reactants and products, reduces the occurrence of deep side reactions, and improves reaction selectivity and catalyst life. At the same time, the first carrier of the catalyst used in the present application has a lower porosity, reduces the infiltration of catalytically active components, improves the utilization efficiency of the catalytically active components of the catalyst, and reduces the removal from the spent catalyst after the catalyst is deactivated and replaced. The difficulty of recovering precious metals also reduces the diffusion of reactants and products into the first carrier, shortens the diffusion distance of reactants and products inside the catalyst, thereby further reducing the occurrence of side reactions and making the reaction more selective . At the same time, the present application achieves a higher conversion rate and selectivity by combining multiple hydrogenation reactors connected in series, and each reactor is independently injected with hydrogen.

Description of the drawings

Fig. 1 is a pore distribution curve of the second carrier of the catalyst prepared in Example 1 of the present application.

Detailed ways

Hereinafter, the present invention will be further described in detail through specific embodiments. It should be understood that the specific embodiments described here are only used to illustrate and explain the present invention, but do not limit the present invention in any way.

Any specific numerical value (including the end point of the numerical range) disclosed in this article is not limited to the precise value of the numerical value, but should be understood to also cover values close to the precise value, for example, within the range of ±5% of the precise value All possible values. Moreover, for the disclosed numerical range, between the endpoints of the range, between the endpoints and the specific point values in the range, and between the specific point values can be combined arbitrarily to obtain one or more new Numerical ranges, these new numerical ranges should also be regarded as specifically disclosed herein.

Unless otherwise specified, the terms used herein have the same meanings as commonly understood by those skilled in the art. If the terms are defined herein and their definitions differ from those commonly understood in the art, the definitions herein shall prevail.

In this application, the "pore distribution curve" refers to the use of mercury intrusion method (ISO 15901-1) to characterize porous materials, the obtained abscissa is the pore size, the coordinate scale is the logarithmic scale, and the ordinate is the pore volume vs. The differential curve of the logarithm of the pore size is, for example, the curve shown in FIG. 1.

In this application, the hole corresponding to the first hole distribution peak on the hole distribution curve is called the first type hole, and the hole corresponding to the second hole distribution peak on the hole distribution curve is called The second type of hole. Correspondingly, the specific pore volume of the pores corresponding to the first pore distribution peak may be referred to as the specific pore volume of the first type of pores, and the specific pore volume of the pores corresponding to the second pore distribution peak may be referred to as the second type of pore. The specific pore volume.

In this application, the "specific pore volume" is calculated on the basis of the quality of the corresponding carrier, and can be measured by the mercury intrusion method (ISO 15901-1).

In this application, the "maximum pore size distribution" refers to the pore size corresponding to the peak of the corresponding pore distribution peak. For example, the maximum pore size distribution of the first type of pore refers to the peak value of the first pore distribution peak. The pore size, and the maximum value of the pore size distribution of the second type of pores refers to the pore size corresponding to the peak of the second pore distribution peak.

In this application, except for the content clearly stated, any matters or matters not mentioned are directly applicable to those known in the art without any changes. Moreover, any implementation described herein can be freely combined with one or more other implementations described herein, and the technical solutions or technical ideas formed thereby shall be regarded as part of the original disclosure or original record of the present invention, and shall not be It is regarded as new content that has not been disclosed or anticipated in this article, unless those skilled in the art think that the combination is obviously unreasonable.

All patent and non-patent documents mentioned in this article, including but not limited to textbooks and journal articles, etc., are incorporated into this article by reference in their entirety.

As described above, the present application provides a method for hydrogenating diolefins to prepare monoolefins, which includes the step of reacting a raw material containing diolefins with hydrogen in the presence of a catalyst, wherein the catalyst includes a support, and the support includes a first support And a second carrier coated on the outer surface of the first carrier, and a catalytically active component supported on the second carrier, wherein the porosity of the first carrier is ≤ 35%, and the thickness of the second carrier The ratio to the effective diameter of the first carrier is between 0.01-0.2, and the pore distribution curve of the second carrier has two pore distribution peaks, wherein the peak of the first pore distribution peak corresponds to the pore diameter in the range of 4-80 nm The pore diameter corresponding to the peak of the second pore distribution peak is in the range of 100-8000 nm.

In a preferred embodiment, the diolefin has 10-15 carbon atoms. More preferably, the feedstock further contains monoolefins having 10-15 carbon atoms.

In a preferred embodiment, the reaction step is performed in a plurality of reactors connected in series, each reactor is provided with a hydrogen injection port, and hydrogen is injected into the corresponding reactor through each hydrogen injection port.

In a further preferred embodiment, the reaction step is carried out in 2-10, preferably 3-5 reactors connected in series, and the hydrogen injection amount of each reactor is 10-50% of the total hydrogen amount, preferably 20-30 %.

In a preferred embodiment, the hydrogenation reaction conditions include: the reaction temperature is 30-250°C, the reaction pressure is 0.1-2.0 MPa, the liquid hourly volumetric space velocity of the reaction is 1-20hr ^-1 , hydrogen and diolefin The total molar ratio is 0.1-5.0.

In a further preferred embodiment, the conditions of the hydrogenation reaction include: the reaction temperature is 50-200°C, the reaction pressure is 0.5-1.0 MPa, the liquid hourly volumetric space velocity of the reaction is 5-10hr ^-1 , hydrogen and double The total molar ratio of olefins is 0.5-2.0.

_{In a preferred embodiment, the content of C 10} -C ₁₅ diolefin in the raw material containing diolefin is 1-3% by weight.

In a particularly preferred embodiment, the method of the present application includes _{passing an alkane/olefin mixture stream containing C 10} -C ₁₅ monoolefins and C ₁₀ -C ₁₅ diolefins through a plurality of series-connected hydrogenation reactors in sequence, in which In contact with the catalyst under the conditions of the hydrogenation reaction, a hydrogen injection port is provided at the inlet of each reactor, and the hydrogen injection amount of each injection port is controlled to adjust the H ₂ /diene molar ratio of each reaction section. The amount of hydrogen injected into the hydrogen injection port of the reactor is controlled so that the hydrogen/diolefin molar ratio of each reactor is independently 10-50%, preferably 20-30%, of the total hydrogen/diolefin molar ratio in the entire hydrogenation reaction. Therefore, on the basis of fully ensuring the conversion of diolefins into monoolefins, the conversion of monoolefins to alkanes is inhibited.

In a further preferred embodiment, the conditions for the hydrogenation reaction include: a reaction temperature of 30-250°C, preferably 50-200°C, a reaction pressure of 0.1-2.0 MPa, preferably 0.5-1.0 MPa, and the liquid-hour volume of the reaction The space velocity is 1-20hr ^-1 , preferably 5-10hr ^-1 , and the total molar ratio of hydrogen to diolefin is 0.1-5.0, preferably 0.5-2.0.

The catalyst used in the present application comprises a first carrier with a relatively low porosity and a second carrier with a porous structure coated on the outer surface of the first carrier, and the catalytically active components are mainly supported on the porous second carrier. In a preferred embodiment, the porosity of the first carrier is ≤25%, more preferably ≤15%. According to this application, the porosity can be measured by mercury intrusion method (ISO 15901-1). In a further preferred embodiment, the specific pore volume of the first carrier is less than or equal to 0.3 ml/g, and the specific surface area of the mercury intrusion method is less than or equal to ^{5 m 2 /g.}

In the catalyst used in the present application, the material constituting the first carrier is a material with low porosity, and the first carrier with low porosity reduces the infiltration of catalytically active components. For catalysts containing platinum, palladium and other precious metals, in order to reduce costs, the precious metals loaded on the spent catalyst will be recycled after the catalyst is deactivated and replaced. The recycling process requires the use of acid or alkali to dissolve the spent catalyst to precipitate the loaded precious metals into the solution. Recycling. However, the substances constituting the first carrier often cannot be completely dissolved by acid and alkali. If the precious metal penetrates into the first carrier more, it is difficult to completely recover it through the chemical process. After the recovery treatment, there will still be more precious metals remaining in the first carrier, resulting in precious metals. The recovery rate is low. In the catalyst used in this application, the material constituting the second carrier can generally be completely dissolved by acid or alkali, and the precious metal components carried in the second carrier are easier to recover; at the same time, the porosity of the first carrier is low This reduces the infiltration of catalytically active components, minimizes the amount of precious metals contained in the first carrier, and thereby reduces the loss when recovering precious metals from the spent catalyst. At the same time, the lower porosity of the first carrier also reduces the inward diffusion of reactants and products, shortens the diffusion distance of reactants and products inside the catalyst, and reduces the occurrence of side reactions.

According to the present application, the pores corresponding to the first pore distribution peak of the second carrier, that is, the first type pores, generally have a pore diameter in the range of 4-200 nm, preferably in the range of 6-100 nm; The pores corresponding to the second pore distribution peak of the second carrier, that is, the second type pores, generally have a pore diameter in the range of 80-10000 nm, preferably in the range of 100-5000 nm.

In a preferred embodiment, the pore diameter corresponding to the peak of the first pore distribution peak of the second carrier is in the range of 8-50 nm, more preferably in the range of 10-50 nm, and the peak of the second pore distribution peak corresponds to the pore diameter It is in the range of 200-3000 nm, more preferably in the range of 200-1000 nm.

In a preferred embodiment, the total specific pore volume of the pores corresponding to the first pore distribution peak and the pores corresponding to the second pore distribution peak of the second carrier (also referred to as the total specific pore volume of the first type of pore and the second type of pore) The specific pore volume) is at least 0.5 ml/g, preferably at least 1.0 ml/g. Further preferably, the pore volume of the pores corresponding to the first pore distribution peak (also referred to as the pore volume of the first type of pore) and the pore volume of the pores corresponding to the second pore distribution peak (also referred to as the pore volume of the second type of pore) The ratio of pore volume) is 1:9 to 9:1, preferably 3:7 to 7:3.

According to the present application, the carrier of the catalyst is composed of a first carrier located inside and a second carrier located outside, respectively, composed of two substances with different properties, and combined. Examples of the constituent material of the first carrier include, but are not limited to, α-alumina, silicon carbide, mullite, cordierite, zirconia, titania, or a mixture thereof. The first carrier can be formed into different shapes as required, such as a spherical shape, a bar shape, a sheet shape, a ring shape, a gear shape, a cylindrical shape, etc., preferably a spherical shape. The effective diameter of the first carrier may be 0.5 mm to 10 mm, preferably 1.2 mm to 2.5 mm. When the first carrier is spherical, the effective diameter refers to the actual diameter of the first carrier; and when the first carrier is non-spherical, the effective diameter refers to when the first carrier is formed In the case of a spherical shape, the diameter of the resulting spherical shape.

According to the present application, examples of the constituent materials of the second support include, but are not limited to, γ-alumina, δ-alumina, η-alumina, θ-alumina, zeolite, non-zeolite molecular sieves, titania, zirconia, Cerium oxide or a mixture thereof, preferably γ-alumina, δ-alumina, zeolite, non-zeolite molecular sieve or a mixture thereof. The second carrier has two different types of pore structures (ie, different pore sizes), and the maximum value of the pore size distribution of the first type of pores is between 4-80 nm, preferably in the range of 8-50 nm, and more preferably in the range of 10-80 nm. In the range of 50 nm, the maximum value of the pore size distribution of the second type of pores is between 100-8000 nm, preferably in the range of 200-3000 nm, more preferably in the range of 200-1000 nm. In a preferred embodiment, the mercury intrusion specific surface area of the second carrier is at least 50 m ² /g, preferably at least 100 m ² /g.

In a preferred embodiment, the catalytically active component of the catalyst includes at least one metal from IUPAC Groups 8-10 and at least one metal selected from IUPAC Groups 1-2 or 11-14. Further preferably, based on the mass of the catalyst, the catalyst contains 0.01%-1% of at least one metal from IUPAC Group 8-10, and 0.01%-2% of at least one metal selected from IUPAC Group 1- Group 2 or Group 11-14 metals.

In a further preferred embodiment, the catalyst contains palladium as the main catalytically active component, and contains a catalytically active component selected from silver, gold, tin, lead, lithium or potassium. Particularly preferably, based on the mass of the catalyst, the catalyst contains 0.01% to 1% of palladium and 0.01% to 2% of catalytically active components.

Long-chain alkanes, especially C ₁₀ -C ₁₅ alkanes, have a relatively large molecular volume. Compared with some small molecular hydrocarbons with low carbon number, long-chain alkenes have greater diffusion resistance in the catalyst, longer residence time, and cause deep side reactions to occur more easily, the selectivity of the target product is low, and the catalyst has serious carbon deposits. The service life is short. The catalyst involved in this application is composed of a combination of two substances with different properties, a first carrier and a second carrier. The catalytic reaction active centers are only distributed on the second carrier in the outer layer, which greatly reduces the amount of reactants and products in the catalyst. Diffusion distance, the second carrier provides two different types of pores. The first type of smaller pores (the maximum pore size distribution is between 4-80nm) provides the high specific surface area and active centers required for the reaction to enable the catalyst to react Increased activity; the second type of larger-sized pores (the maximum pore size distribution is 100-8000nm) are used as diffusion channels for reactants and products, which greatly reduces the diffusion time of reactants and products, and improves the diffusion of reactants and products. During the process, the diffusion resistance of reactants and products is reduced, and the residence time in the catalyst is reduced, thereby reducing the occurrence of side reactions, increasing the selectivity of the target product, effectively improving the reaction efficiency of the catalyst, and reducing the formation of carbon deposits With accumulation, the service life of the catalyst is prolonged. The catalyst involved in this application is preferably palladium as the main catalytic element, and there is no need to use sulfur injection methods to improve the selectivity of diolefin hydrogenation to monoolefins, and avoid the complicated operation, unstable operation, and investment caused by the need for sulfur injection for nickel-containing catalysts. Higher shortcomings, low reaction temperature, lower energy consumption, and more environmentally friendly. The hydrogenation method involved in this application adopts a multi-stage hydrogenation method. By controlling the hydrogen/diolefin molar ratio added to each reactor, the selectivity and conversion rate of the conversion of diolefins to monoolefins are increased, and the hydrogenation of monoolefins is avoided The product yield decreased due to conversion to alkanes, thereby increasing the yield of monoolefins. By applying the above several methods in combination to hydrogenate diolefins to produce monoolefins, especially for the _{hydrogenation of C 10} -C ₁₅ diolefins to produce monoolefins, particularly excellent effects have been obtained and the deficiencies of the previous inventions have been overcome. Greatly improve the _{selectivity and yield of C 10} -C ₁₅ diolefin hydrogenation to monoolefin.

In some preferred embodiments, the catalyst is prepared by a method including the following steps:

1) Shape the raw material of the first carrier into a predetermined shape, react for 5-24 hours in an air atmosphere at 40-90°C and a relative humidity of ≥80%, dry and calcinate to obtain a material selected from the group consisting of α-alumina, silicon carbide, A first carrier composed of mullite, cordierite, zirconium oxide, titanium oxide or a mixture thereof;

2) Combine porous materials selected from γ-alumina, δ-alumina, η-alumina, θ-alumina, zeolite, non-zeolite molecular sieves, titanium oxide, zirconium oxide, cerium oxide or mixtures thereof with optional manufacturing The porogen is made into slurry, and the resulting slurry is applied to the outer surface of the first carrier, dried and fired to obtain a carrier comprising a first carrier and a second carrier coated on the outer surface of the first carrier. The pore distribution curve of the porous material has one pore distribution peak, and the pore distribution peak corresponding to the pore size is in the range of 4-80 nm, or the pore distribution curve of the porous material has two pore distribution peaks, wherein the first pore distribution peak The pore diameter corresponding to the peak of the second pore distribution peak is in the range of 4-80nm, and the pore diameter corresponding to the peak of the second pore distribution peak is in the range of 100-8000nm;

3) Impregnating the carrier obtained in step 2) with a solution containing catalytically active components, drying and calcining, and optionally performing steam treatment to obtain a catalyst precursor; and

4) The catalyst precursor obtained in step 3) is reduced with hydrogen to obtain a catalyst product.

The molding of the first carrier can be based on the characteristics of the constituent materials using carrier molding methods known in the art, such as compression molding, extrusion molding, rolling ball molding, drop ball molding, pelletizing molding, melt molding, and the like. According to the difference of the first carrier material, molding generally requires adding 2-20% of the weight of the raw material powder to one or more of inorganic or organic acids such as nitric acid, hydrochloric acid, citric acid, and glacial acetic acid. And a small amount of water, fully mixed and molded. The molded first carrier needs to continue to react for 5 to 24 hours under the conditions of 40 to 90 ℃ and air relative humidity ≥ 80%, and maintain the humidity environment at a suitable temperature to promote the crystal structure Fully transform, and then dry at 100 to 150 ℃ for 2 to 8 hours. The first carrier after drying needs to be calcined at a certain temperature to form a low-porosity structure. The calcining temperature should be at least higher than the catalyst temperature, which is generally 350 to 1700°C according to the characteristics of different materials. The fired first carrier is a substance with a low porosity, specifically, a substance with a specific pore volume ≤ 0.3 ml/g, a mercury injection method specific surface area ^{≤ 5 m 2} /g, and a porosity ≤ 35%.

The raw materials used to prepare the first carrier are well known to those skilled in the art and can be selected according to the constituent materials of the first carrier. For example, when the first carrier is mullite, alumina and silica can be used as raw materials to synthesize by a sintering method; when the first carrier is α-alumina, aluminum hydroxide can be obtained by high-temperature sintering as a raw material.

The combination of the second carrier and the first carrier can be achieved by first forming a slurry of the second carrier material, and then applying the resulting slurry to the outer surface of the first carrier by conventional methods such as dipping, spraying, coating, etc. To achieve, but not limited to the above several coating methods. The preparation of the second carrier material slurry usually includes a peptizing process. The second carrier material with a porous structure and water are mixed and stirred in a certain ratio. Usually, a certain amount of peptizing agent, such as nitric acid, hydrochloric acid or organic acid, is added. The dosage accounts for 0.01% to 5% of the total slurry. The thickness of the second carrier can be controlled by the amount of the second carrier material slurry.

According to the present application, the thickness of the second carrier can be determined according to the effective diameter of the first carrier, thereby obtaining the best catalytic reaction performance. Generally, the thickness of the second carrier is equal to the effective diameter of the first carrier. The ratio is between 0.01-0.2.

The second carrier with two types of pores can be directly prepared from a porous material with a desired pore structure, or can be prepared from a porous material with a certain pore structure combined with a suitable amount of pore former. For example, the second carrier may be directly made of a porous material having two types of pores (for example, the maximum value of the pore size distribution is in the range of 4-80nm and 100-8000nm, respectively); it may also be made of only one type of pores. (For example, the maximum value of the pore size distribution is in the range of 4-80 nm). The porous material is made by combining a suitable amount of pore former. According to the required pore size, the pore former can be selected from sesame powder, methyl cellulose, polyvinyl alcohol, carbon black and other materials, but it is not limited to these, and the addition amount is controlled to form the second carrier 5%-50% of the mass of the porous material. The second carrier of the finally prepared catalyst has two types of pores. The maximum value of the pore size distribution of the first type of pores is between 4-80 nm, preferably in the range of 8-50 nm, more preferably in the range of 10-50 nm, The maximum value of the pore size distribution of the second type of pores is between 100-8000 nm, preferably in the range of 200-3000 nm, more preferably in the range of 200-1000 nm. The pore volume provided by the first type of hole accounts for 10%-90% of the total pore volume, preferably 30%-70%, and the pore volume provided by the second type of pores accounts for 90%-10% of the total pore volume, preferably 70%-30 %.

The combination of the second carrier and the first carrier needs to be calcined at a high temperature to complete. For example, the first carrier coated with the porous material slurry is dried at 60-200°C for 0.5-10 hours, and then calcined at 300-1000°C for a sufficient time, such as 2-15 hours, to obtain the first carrier and the package. The carrier of the second carrier covering the outer surface of the first carrier.

Each catalytically active component can be supported on the aforementioned support by means of impregnation. One method is to make each catalytically active component into a mixed solution and contact the mixed solution with the carrier; the other method is to contact the solution of each catalytically active component with the carrier one by one. Dry the carrier impregnated with catalytically active components at 100-200°C for 2-8 hours, then calcinate at 300-600°C for 2-8 hours, and pass water vapor at 200-700°C for further treatment for 0.5-4 hours; Then, it is reduced with hydrogen at room temperature to 300°C, preferably 60-150°C, for 0.5-10 hours, preferably 1-5 hours, to obtain the catalyst.

In some preferred embodiments, this application provides the following technical solutions:

1. A method for hydrogenating diolefins to monoolefins, characterized in that the mixture of the diolefins and the monoolefins is contacted with a catalyst under hydrogenation reaction conditions in a plurality of reactors connected in series The inlet of each reactor has a hydrogen injection port, and hydrogen is injected into the reactor through each hydrogen injection port. The catalyst includes a carrier and at least one catalytic component supported on the carrier. It includes at least a first layer carrier and a second layer carrier, the second layer carrier encapsulates the first layer carrier from space, and the second layer carrier deposits at least one of the catalytic components, so The ratio of the thickness of the second layer of carrier to the effective diameter of the first layer of carrier is between 0.01-0.2, and the second layer of carrier is distributed with a first type of pores and a second type of pores, and the first type of pores The maximum value of the pore size distribution of the pores is between 4-50 nm, and the maximum value of the pore size distribution of the second type of pores is between 100-1000 nm.

2. The method according to item 1, characterized in that the diolefin contains 10 to 15 carbon atoms.

3. The method according to item 1, characterized in that the pore size distribution range of the first type pores is between 10-20 nm, and the pore size distribution range of the second type pores is between 150-500 nm.

4. The method according to item 1, characterized in that the method comprises combining the at least one IUPAC group 8-10 metal and at least one metal selected from the IUPAC group 1-2 or 11-14 The step of depositing onto the second layer of carrier.

5. The method according to item 1, characterized in that the amount of hydrogen injected into each reactor inlet is such that the hydrogen/diolefin molar ratio injected into each reactor accounts for the total hydrogen/diolefin molar ratio in the selective hydrogenation reaction. Of 10-50%.

6. The method according to item 5, characterized in that the amount of hydrogen injected into each reactor inlet is such that the hydrogen/diolefin molar ratio injected into each reactor accounts for the total hydrogen/diolefin molar ratio in the selective hydrogenation reaction. Of 20-30%.

7. The method according to item 1, characterized in that the hydrogenation reaction conditions are: the reaction temperature is 30-250°C, the reaction pressure is 0.1-2MPa, the liquid hourly space velocity of the reaction is 1-20hr ^-1 , and hydrogen The total molar ratio to diolefins is 0.1-5.0.

8. The method according to item 7, wherein the hydrogenation reaction conditions are: the reaction temperature is 50-200°C, the reaction pressure is 0.5-1.0 MPa, and the liquid hourly space velocity of the reaction is 5-10hr ^-1 , The total molar ratio of hydrogen to diolefin is 0.5-2.0.

9. The method according to item 1, wherein the _{content of C 10} -C ₁₅ diolefin in the mixture is 1-3% by weight.

10. The method according to item 1, characterized in that the pore volume of the first layer of carrier is ≤ 0.3 ml/g, and the BET specific surface area is ≤ ²⁰ m 2 /g.

Example

Hereinafter, the present application will be described in detail through examples, but they do not constitute any limitation to the present application.

In the following examples and comparative examples, the specific pore volume, porosity and specific surface area of the first and second carriers, as well as the pore distribution of the second carrier, adopt the mercury intrusion method (ISO 15901-1 Evaluation of pore size distribution and porosity of Solid materials by mercury porosimetry and gas adsorption) were used for characterization. The instrument used was the Poremaster GT60 Mercury Porosimetry Analyzer from Quantachrome Instrument, and the test conditions were a contact angle of 140° and a mercury surface tension of 0.4842 N·m ^{-1 at} 25°C. The post-processing software is Poremaster for Windows. The pore distribution curve of the second carrier is obtained by mapping the measured data with Origin software.

In the following examples and comparative examples, the catalytically active component content of the catalyst obtained was determined by X-ray fluorescence spectrometry, the instrument used was ADVANT'TP X-ray fluorescence spectrometer from ARL Company, and the test conditions were Rh target, 40kV/ 60mA.

In the following examples and comparative examples, the crystal form of the carrier material is determined by X-ray powder diffraction (XRD), the instrument used is ARL X'TRA X-ray diffractometer, the test conditions are Cu target, Kα rays (wavelength λ = 0.154nm), the tube voltage is 45kV, the tube current is 200mA, and the scanning speed is 10°(2θ)/min.

In the following examples and comparative examples, the thickness of the second carrier is measured by scanning electron microscopy (SEM), the instrument used is a Hitachi TM3000 desktop microscope, and the test condition is that the sample is fixed on the sample stage with conductive glue for observation, and the voltage is 15kV.

In the following examples and comparative examples, the alumina powder with two types of pores used to prepare the second carrier was prepared with reference to the method disclosed in Chinese Patent Application CN1120971A, and other alumina and aluminum hydroxide powders were purchased from Shandong Aluminum Industry Co., Ltd.

Unless otherwise specified, the reagents used in the following examples and comparative examples are all analytically pure, and all are commercially available.

Example 1 Preparation of Catalyst A

In this embodiment, alumina powder with two types of pores is used to prepare the second carrier, and mullite is used as the first carrier to effectively combine to obtain a carrier containing two layers of inner and outer layers, and to prepare a catalyst.

Take 500 grams of alumina powder (purity 98.6%), 196 grams of silica powder (purity 99.0%), 70 grams of water, 10 grams of 10% nitric acid, mix, knead for 1 hour, press into small balls, 70℃, ≥80% The reaction was continued under relative humidity for 10 hours, then dried at 150°C for 2 hours, and then calcined at 1450°C for 3 hours to obtain the first carrier pellets with a diameter of 2.0 mm. XRD analysis showed that it was mullite crystal form.

The prepared first carrier was characterized by mercury intrusion method, and the results showed that the specific pore volume of the first carrier was 0.09 ml/g, the specific surface was 0.21 m ² /g, and the porosity was 12%.

Take 50 grams of alumina powder (with two types of pores, the maximum value of the pore size distribution of the two types of pores is 27 nm and 375 nm, respectively), 20 grams of 20% nitric acid, and 600 grams of water are mixed and stirred for 2 hours to prepare an alumina slurry. The slurry was sprayed on the first carrier ball with a diameter of 2.0 mm with a spray gun. The pellets coated with the slurry were dried at 100°C for 6 hours, and then calcined at 500°C for 6 hours to obtain a carrier containing two layers of inner and outer layers. SEM analysis showed that the thickness of the second carrier was 150 μm, and the ratio to the diameter of the first carrier was 0.075.

The prepared carrier was impregnated with 0.4 mol/l palladium chloride solution, dried at 120°C for 5 hours, calcined at 550°C for 6 hours, and treated with steam at 550°C for 1 hour. Then, it was impregnated with 0.25 mol/l silver nitrate solution, dried at 120°C for 5 hours, calcined at 550°C for 8 hours, and then reduced with hydrogen with a purity greater than 99% at 120°C for 2 hours to prepare catalyst A . Measured by X-ray fluorescence spectrometry, based on the mass of the catalyst, the content of each catalytically active component is 0.12% palladium and 0.3% silver.

The second carrier coated on the outer surface of the first carrier is peeled off mechanically, and the second carrier is characterized by mercury intrusion method. The obtained pore distribution curve is shown in FIG. 1. It can be seen from Figure 1 that the pore distribution curve of the second carrier of the catalyst has two pore distribution peaks, indicating that there are two types of pores with different sizes in the second carrier, and the pore size distribution of the first type of pore The maximum value (ie the pore size value corresponding to the peak of the first pore distribution peak in the curve, the same below) is 22nm, and the maximum value of the pore size distribution of the second type of hole (ie the peak value of the second pore distribution peak in the curve corresponds to The aperture value, the same below) is 412nm. Based on the mass of the second carrier, the specific pore volume of the first type of pore is 0.98 ml/g, the specific pore volume of the second type of pore is 0.72 ml/g, and the total specific pore volume is 1.70 ml/g. The specific surface area of the second carrier measured by mercury intrusion method was 152 m ² /g. According to XRD measurement, the crystal form of the second carrier is γ-alumina.

Example 2 Preparation of Catalyst B

In this embodiment, the alumina powder with one type of pores and the pore-forming agent methylcellulose are added to prepare the second carrier with two types of pores, and mullite is used as the first carrier to effectively combine the inside and outside. A two-layer carrier and a catalyst are prepared.

The first carrier was prepared according to the method of Example 1.

Take 50 grams of alumina powder (with one type of pores, the maximum pore size distribution is 25 nm), 20 grams of 20% nitric acid, 12 grams of methyl cellulose, and 600 grams of water are mixed and stirred to prepare an alumina slurry. Refer to the method of Example 1 for molding, and appropriately adjust the amount of alumina slurry to obtain a carrier containing two layers of inner and outer layers. SEM analysis showed that the thickness of the second carrier was 120 μm, and the ratio to the diameter of the first carrier was 0.06.

The catalyst B was obtained according to the catalyst preparation method of Example 1. Measured by X-ray fluorescence spectrometry, based on the mass of the catalyst, the content of each catalytically active component is 0.12% palladium and 0.3% silver.

With reference to Example 1 for characterization by mercury intrusion method, it is found that there are two types of pores in the second support of the catalyst. The maximum value of the pore size distribution of the first type of pore is 19 nm, and the maximum value of the pore size distribution of the second type of pore is 252 nm. Based on the mass of the second carrier, the specific pore volume of the first type of pore is 0.9ml/g, the specific pore volume of the second type of pore is 0.6ml/g, and the total specific pore volume is 1.50ml/g. The specific surface area of the second carrier measured by mercury intrusion method was 135 m ² /g. According to XRD measurement, the crystal form of the second carrier is γ-alumina.

Example 3 Preparation of Catalyst C

In this embodiment, alumina powder with two types of pores is used to prepare the second carrier, and mullite is used as the first carrier to effectively combine to obtain a carrier containing two layers of inner and outer layers, and to prepare a catalyst.

The first carrier was prepared according to the method of Example 1.

Take 50 grams of alumina powder (with two types of pores, the maximum value of the pore size distribution of the two types of pores is 20 nm and 516 nm, respectively), 20 grams of 20% nitric acid, and 600 grams of water are mixed and stirred for 2 hours to prepare an alumina slurry. Refer to the method of Example 1 for molding, and appropriately adjust the amount of alumina slurry to obtain a carrier containing two layers of inner and outer layers. SEM analysis showed that the thickness of the second carrier was 220 μm, and the ratio to the diameter of the first carrier was 0.11.

The catalyst C was obtained according to the catalyst preparation method of Example 1. Measured by X-ray fluorescence spectrometry, based on the mass of the catalyst, the content of each catalytically active component is 0.12% palladium and 0.3% silver.

With reference to Example 1 for characterization by mercury intrusion method, it is found that there are two types of pores in the second support of the catalyst, the maximum value of the pore size distribution of the first type of pore is 15 nm, and the maximum value of the pore size distribution of the second type of pore is 652 nm. Based on the mass of the second carrier, the specific pore volume of the first type is 0.91ml/g, the specific pore volume of the second type is 0.69ml/g, and the total specific pore volume is 1.60ml/g. The specific surface area of the second carrier measured by mercury intrusion method was 145 m ² /g. According to XRD measurement, the crystal form of the second carrier is γ-alumina.

Example 4 Preparation of Catalyst D

In this embodiment, alumina powder with two types of pores is used to prepare the second carrier, and mullite is used as the first carrier to effectively combine to obtain a carrier containing two layers of inner and outer layers, and to prepare a catalyst.

The first carrier was prepared according to the method of Example 1.

Take 50 grams of alumina powder (with two types of pores, the maximum value of the pore size distribution of the two types of pores is 12 nm and 100 nm, respectively), 20 grams of 20% nitric acid, and 600 grams of water are mixed and stirred for 2 hours to prepare an alumina slurry. Refer to the method of Example 1 for molding, and appropriately adjust the amount of alumina slurry to obtain a carrier containing two layers of inner and outer layers. SEM analysis showed that the thickness of the second carrier was 70 μm, and the ratio to the diameter of the first carrier was 0.035.

The catalyst D was obtained according to the catalyst preparation method of Example 1. Measured by X-ray fluorescence spectrometry, based on the mass of the catalyst, the content of each catalytically active component is 0.12% for palladium and 0.3% for silver.

Refer to Example 1 for characterization by mercury intrusion method, and it is found that there are two types of pores in the second support of the catalyst. The maximum value of the pore size distribution of the first type of pore is 9 nm, and the maximum value of the pore size distribution of the second type of pore is 120 nm. Based on the mass of the second carrier, the specific pore volume of the first type is 0.58ml/g, the specific pore volume of the second type is 0.82ml/g, and the total specific pore volume is 1.40ml/g. The specific surface area of the second carrier measured by mercury intrusion method was 122 m ² /g. According to XRD measurement, the crystal form of the second carrier is γ-alumina.

Example 5 Preparation of Catalyst E

In this embodiment, alumina powder with two types of pores is used to prepare the second carrier, and α-alumina is used as the first carrier to effectively combine to obtain a carrier containing two layers of inner and outer layers, and prepare a catalyst.

Take 800 grams of aluminum hydroxide powder (purity 99%) and roll it into small balls. Place them at 70°C and ≥80% relative humidity and continue to react for 20 hours, then dry at 120°C for 2 hours, and then at 1100 It is calcined at ℃ for 5 hours to obtain a small ball with a diameter of 2.0 mm as the first carrier. XRD analysis showed that it was α-alumina crystal form.

Refer to the method of Example 1 to form a carrier containing two layers of inner and outer layers, and appropriately adjust the amount of alumina slurry. SEM analysis showed that the thickness of the second carrier was 150 μm, and the ratio to the diameter of the first carrier was 0.075.

The prepared carrier was impregnated with 0.4 mol/l palladium chloride solution, dried at 120°C for 5 hours, calcined at 550°C for 6 hours, and treated with steam at 550°C for 1 hour. Then, it was impregnated with 0.25mol/l lithium nitrate solution, dried at 120°C for 5 hours, calcined at 550°C for 8 hours, and then reduced with hydrogen with a purity greater than 99% at 120°C for 2 hours to prepare catalyst E . Measured by X-ray fluorescence spectrometry, based on the mass of the catalyst, the content of each catalytically active component is 0.12% palladium and 0.2% lithium.

With reference to Example 1 for characterization by mercury intrusion method, it was found that there are two types of pores in the second layer of the catalyst. The maximum value of the pore size distribution of the first type of pores is 20 nm, and the maximum value of the pore size distribution of the second type of pores is 410 nm. . Based on the quality of the second carrier, the specific pore volume of the first type is 0.96ml/g, the specific pore volume of the second type is 0.70ml/g, and the total specific pore volume is 1.66ml/g. The specific surface area of the second carrier measured by mercury intrusion method was 148 m ² /g. According to XRD measurement, the crystal form of the second carrier is γ-alumina.

Example 6 Preparation of Catalyst F

In this embodiment, the alumina powder with one type of pores and the pore-forming agent methylcellulose are added to prepare the second carrier with two types of pores, and mullite is used as the first carrier to effectively combine the inside and outside. A two-layer carrier and a catalyst are prepared.

The first carrier was prepared according to the method of Example 1.

Take 50 grams of alumina powder (with one type of pores, the maximum pore size distribution is 28 nm), 18 grams of 20% nitric acid, 10 grams of methyl cellulose, and 600 grams of water are mixed and stirred to prepare an alumina slurry. The slurry was sprayed on the first carrier ball with a diameter of 2.0 mm with a spray gun. The pellets coated with the slurry were dried at 100°C for 6 hours, and then calcined at 900°C for 6 hours to obtain a carrier containing two layers of inner and outer layers. SEM analysis showed that the thickness of the second carrier was 110 μm, and the ratio to the diameter of the first carrier was 0.055.

The catalyst F was obtained according to the catalyst preparation method of Example 1. Measured by X-ray fluorescence spectrometry, based on the mass of the catalyst, the content of each catalytically active component is 0.12% palladium and 0.3% silver.

Refer to Example 1 for characterization by mercury intrusion method. It is found that there are two types of pores in the second layer of the catalyst. The maximum value of the pore size distribution of the first type of pore is 30 nm, and the maximum value of the pore size distribution of the second type of pore is 280 nm. . Based on the mass of the second carrier, the specific pore volume of the first type is 0.49ml/g, the specific pore volume of the second type is 0.57ml/g, and the total specific pore volume is 1.06ml/g. The specific surface area of the second carrier measured by mercury intrusion method was 106 m ² /g. According to the XRD measurement in Example 1, the crystal form of the second support is δ-alumina.

Comparative Example 1 Preparation of Catalyst G

In this embodiment, alumina powder with two types of pores is used to prepare the second carrier, and mullite is used as the first carrier to effectively combine to obtain a carrier containing two layers of inner and outer layers, and to prepare a catalyst.

Take 500 grams of alumina powder (purity 98.6%), 196 grams of silica powder (purity 99.0%), 70 grams of water, 10 grams of 10% nitric acid, mix, knead for 1 hour, press into pellets, and then bake at 150 ℃ Dry for 2 hours, and then calcinate at 1450°C for 1 hour to obtain first carrier pellets with a diameter of 2.0 mm. XRD analysis showed that it was mullite crystal form.

The prepared first carrier was characterized by mercury intrusion method, and the result showed that the specific pore volume of the first carrier was 0.32 ml/g, the specific surface was 8.5 m ² /g, and the porosity was 38%.

Refer to the method of Example 1 to form a carrier containing two layers of inner and outer layers, and appropriately adjust the amount of alumina slurry. SEM analysis showed that the thickness of the second carrier was 150 μm, and the ratio to the diameter of the first carrier was 0.075.

The catalyst G was obtained according to the catalyst preparation method of Example 1. Measured by X-ray fluorescence spectrometry, based on the mass of the catalyst, the content of each catalytically active component is 0.12% of palladium and 0.3% of silver.

With reference to Example 1 for characterization by mercury intrusion method, it is found that there are two types of pores in the second support of the catalyst, the maximum value of the pore size distribution of the first type of pore is 22 nm, and the maximum value of the pore size distribution of the second type of pore is 420 nm. Based on the mass of the second carrier, the specific pore volume of the first type is 0.98ml/g, the specific pore volume of the second type is 0.71ml/g, and the total specific pore volume is 1.69ml/g. The specific surface area of the second carrier measured by mercury intrusion method was 155 m ² /g. According to XRD measurement, the crystal form of the second carrier is γ-alumina.

Comparative Example 2 Preparation of Catalyst H

In this embodiment, alumina powder with one type of pores is used to prepare the second carrier, and mullite is used as the first carrier to effectively combine to obtain a carrier containing two layers of inner and outer layers, and to prepare a catalyst.

The first carrier was prepared according to the method of Example 1.

Take 50 grams of alumina powder (with one type of pores, the maximum pore size distribution is 22 nm), 20 grams of 20% nitric acid, and 600 grams of water are mixed and stirred for 2 hours to prepare an alumina slurry. The slurry was sprayed on the first carrier ball with a diameter of 2.0 mm with a spray gun. The pellets coated with the slurry were dried at 100°C for 6 hours, and then calcined at 500°C for 6 hours to obtain a carrier containing two layers of inner and outer layers. SEM analysis showed that the thickness of the second carrier was 110 μm, and the ratio to the diameter of the first carrier was 0.055.

The catalyst H was obtained according to the catalyst preparation method of Example 1. Measured by X-ray fluorescence spectrometry, based on the mass of the catalyst, the content of each catalytically active component is 0.12% palladium and 0.3% silver.

With reference to Example 1, the mercury intrusion method was used for characterization, and it was found that only one type of pores existed in the second support of the catalyst, and the maximum pore size distribution was 16 nm. Based on the mass of the second carrier, the specific pore volume is 1.15ml/g. The specific surface area of the second carrier measured by mercury intrusion method was 180 m ² /g. According to XRD measurement, the crystal form of the second carrier is γ-alumina.

Comparative Example 3 Preparation of Catalyst I

In this example, an alumina spherical support with two types of pores and a radially uniform composition was prepared, and a catalyst was prepared.

Take 50 grams of alumina powder (with two types of pores, and the maximum pore size distribution of the two types of pores are 15 nm and 250 nm, respectively), 20 grams of 20% nitric acid, and 200 grams of water are mixed and stirred to prepare an alumina slurry. The slurry is formed into pellets by a method of forming an oil column, dried at 100°C for 6 hours, and then calcined at 500°C for 6 hours to obtain a radially uniform carrier.

The catalyst I was obtained according to the catalyst preparation method of Example 1. Measured by X-ray fluorescence spectrometry, based on the mass of the catalyst, the content of each catalytically active component is 0.12% palladium and 0.3% silver.

The catalyst I was characterized by mercury intrusion method, and it was found that there were two types of pores in the catalyst. The maximum pore size distribution of the first type of pores was 19nm, the specific pore volume of the first type was 0.91ml/g, and the second type of pores had a specific pore volume of 0.91ml/g. The maximum pore size distribution is 370nm, the specific pore volume of the second type is 0.70ml/g, and the total specific pore volume is 1.61ml/g. The specific surface area of the carrier measured by mercury intrusion method is 160 m ² /g. According to XRD measurement, the crystal form of the second carrier is γ-alumina.

Comparative Example 4 Preparation of Catalyst J

In this embodiment, alumina powder with two types of pores is used to prepare the second carrier, and mullite is used as the first carrier to effectively combine to obtain a carrier containing two layers of inner and outer layers, and to prepare a catalyst.

The first carrier was prepared according to the method of Example 1.

Take 50 grams of alumina powder (with two types of pores, the maximum pore size distribution of the two types of pores is 26 nm and 384 nm respectively), 20 grams of 20% nitric acid, and 600 grams of water are mixed and stirred for 2 hours to prepare an alumina slurry. The slurry was sprayed on the first carrier pellet with a diameter of 1.3 mm with a spray gun. The pellets coated with the slurry were dried at 100°C for 6 hours, and then calcined at 500°C for 6 hours to obtain a carrier containing two layers of inner and outer layers. SEM analysis showed that the thickness of the second carrier was 350 μm, and the ratio to the diameter of the first carrier was 0.27.

The catalyst J was obtained according to the catalyst preparation method of Example 1. Measured by X-ray fluorescence spectrometry, based on the mass of the catalyst, the content of each catalytically active component is 0.12% palladium and 0.3% silver.

With reference to Example 1 for characterization by mercury intrusion method, it is found that there are two types of pores in the second support of the catalyst, the maximum value of the pore size distribution of the first type of pore is 21 nm, and the maximum value of the pore size distribution of the second type of pore is 450 nm. Based on the mass of the second carrier, the specific pore volume of the first type is 0.96ml/g, the specific pore volume of the second type is 0.75ml/g, and the total specific pore volume is 1.71ml/g. The specific surface area of the second carrier measured by mercury intrusion method was 153 m ² /g. According to XRD measurement, the crystal form of the second carrier is γ-alumina.

Example 7 Analysis of Pd content in the first carrier of the catalyst

The catalyst A obtained in Example 1 was digested with 15 wt% hydrochloric acid to remove the second carrier, and the Pd content of the remaining first carrier was analyzed by X-ray fluorescence spectrometry. The results show that based on the mass of the first carrier, the Pd content in the first carrier is 0.0008 wt%.

Comparative Example 5 Analysis of Pd content in the first carrier of the catalyst

The catalyst G obtained in Comparative Example 1 was digested with 15 wt% hydrochloric acid to remove the second carrier, and the Pd content of the remaining first carrier was analyzed by X-ray fluorescence spectrometry. The results showed that based on the mass of the first carrier, the Pd content in the first carrier was 0.014 wt%.

By comparing the data of Comparative Example 1 and Example 1, it can be seen that the specific pore volume of the first carrier prepared by the method of Example 1 is 0.09ml/g, the specific surface is 0.21m ² /g, the porosity is 12%, and the porosity is The specific pore volume of the first carrier prepared by the method of Comparative Example 1 is 0.32 ml/g, the specific surface area is 8.5 m ² /g, the porosity is 38%, and the porosity is relatively high. At the same time, by comparing the data of Comparative Example 5 and Example 7, it can be seen that after acid cooking, the content of residual Pd in the catalyst A with low porosity of the first carrier is 0.0008wt%, which is much less than the porosity of the first carrier. The content of Pd remaining in the high catalyst G is 0.014 wt%. The above results indicate that the low-porosity first carrier of catalyst A reduces the entry of Pd, so that catalyst A has a higher recovery rate of Pd, the use efficiency of precious metals is higher, and the use cost of the catalyst is lower.

Example 8 Diolefin hydrogenation reaction

Respectively, 100 liters of the catalysts prepared in the above examples and comparative examples were equally divided into 4 reactors, and the 4 reactors were used in series. The reaction temperature was controlled at 130°C, the pressure was 0.8MPa, and the LHSV=5.0 hr ^-1 , H ₂ /diolefin (molar ratio) = 1, the hydrogen injection volume in each stage of the reactor is a quarter of the total hydrogen injection volume. After the material containing _{2.6% by weight of C 10} -C ₁₅ diolefins is selectively hydrogenated under the above conditions, the conversion rate of diolefins and the selectivity of the monoolefins produced are calculated, where:

Diolefin conversion rate = (mass content of diolefins in the raw material-mass content of diolefins in the product)/mass content of diolefins in the raw material * 100%;

Mono-olefin selectivity=(mass content of mono-olefins in the product-mass content of mono-olefins in the feedstock)/(mass content of the diolefins in the feedstock-mass content of the diolefins in the product)*100%.

The results obtained are shown in Table 1:

Table 1 Comparison of hydrogenation reaction results of different catalysts

catalyst Conversion rate of diolefin,% Mono-olefin selectivity,% A 87.6 71.3 B 86.4 73.5 C 91.5 77.6 D 84.2 69.1 E 85.5 75.7 F 82.4 72.1 G 80.6 61.2 H 68.5 55.5 I 77.4 41.8 J 75.1 53.1

It can be seen from the data in Table 1 that the six catalysts A, B, C, D, E, and F with double-layer supports and two types of pore structures prepared in Examples 1-6 of this application are more effective than catalysts H and I. The conversion rate and selectivity are significantly improved. The conversion rate and selectivity of the catalyst A with the first support with a low porosity are higher than those of the catalyst G with the first support with a higher porosity. The ratio of the thickness of the second support to the effective diameter of the first support is between 0.01 and 0.2. The conversion rate and selectivity of catalysts A, B, C, D, E, and F are all higher than the thickness and selectivity of the second support. The catalyst J in which the ratio of the effective diameter of the first carrier is not between 0.01 and 0.2.

Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the embodiments of the present application, but not to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: The technical solutions recorded in the foregoing embodiments can still be modified, or some of the technical features can be equivalently replaced; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and spirit of the technical solutions of the embodiments of the present application. range.

Claims (10)

The method for preparing monoolefins by hydrogenating diolefins includes the step of reacting a raw material containing diolefins with hydrogen in the presence of a catalyst, wherein the catalyst includes a support, the support including a first support and a coating on the outer surface of the first support The second carrier, and the catalytically active component supported on the second carrier, wherein the porosity of the first carrier is less than or equal to 35%, and the thickness of the second carrier is less than the effective diameter of the first carrier The ratio is between 0.01-0.2, the pore distribution curve of the second carrier has two pore distribution peaks, wherein the pore diameter corresponding to the peak of the first pore distribution peak is in the range of 4-80 nm, preferably in the range of 8-50 nm, It is more preferably in the range of 10-50 nm, and the pore diameter corresponding to the peak of the second pore distribution peak is in the range of 100-8000 nm, preferably in the range of 200-3000 nm, more preferably in the range of 200-1000 nm. The method of claim 1, wherein the catalyst has one or more of the following characteristics: The total specific pore volume of the pores corresponding to the first pore distribution peak and the pores corresponding to the second pore distribution peak is at least 0.5 ml/g, preferably at least 1.0 ml/g; The ratio of the pore volume of the pores corresponding to the first pore distribution peak to the pore volume of the pores corresponding to the second pore distribution peak is 1:9 to 9:1, preferably 3:7 to 7:3. The method according to any one of the preceding claims, wherein the catalyst has one or more of the following characteristics: The second carrier is composed of a material selected from the group consisting of γ-alumina, δ-alumina, η-alumina, θ-alumina, zeolite, non-zeolite molecular sieve, titanium oxide, zirconia, cerium oxide or a mixture thereof; and The mercury intrusion specific surface area of the second carrier is at least 50 m ² /g, preferably at least 100 m ² /g. The method according to any one of the preceding claims, wherein the catalyst has one or more of the following characteristics: The specific pore volume of the first carrier is less than or equal to 0.3 ml/g, and the specific surface area of the mercury injection method is less than or equal to ^{5 m 2 /g;} The porosity of the first carrier is ≤25%, more preferably ≤15%; The first carrier is made of a material selected from the group consisting of α-alumina, silicon carbide, mullite, cordierite, zirconia, titania or a mixture thereof; The first carrier is spherical, bar-shaped, sheet-shaped, ring-shaped, gear-shaped or cylindrical, preferably spherical; and The effective diameter of the first carrier is 0.5 mm to 10 mm, preferably 1.2 mm to 2.5 mm. The method according to any one of the preceding claims, wherein the catalytically active component of the catalyst comprises at least one metal selected from IUPAC Groups 8-10 and at least one metal selected from IUPAC Groups 1-2 or Group 11-14 metals. The method according to any one of the preceding claims, wherein the diolefin has 10-15 carbon atoms; preferably, the feedstock further comprises a monoolefin having 10-15 carbon atoms. The method according to any one of the preceding claims, wherein the _{content of C 10} -C ₁₅ diolefins in the feedstock is 1-3% by weight. The method according to any one of the preceding claims, wherein the reaction step is carried out in a plurality of reactors connected in series, each reactor is provided with a hydrogen injection port, and hydrogen passes through each hydrogen injection port. Pour into the corresponding reactor. The method according to claim 8, wherein the reaction step is carried out in 2-10, preferably 3-5 reactors connected in series, and the hydrogen injection amount of each reactor is independently 10-50 of the total hydrogen amount. %, preferably 20-30%. The method according to any one of the preceding claims, wherein the conditions of the reaction include: a reaction temperature of 30-250°C, a reaction pressure of 0.1-2 MPa, and a liquid hourly volumetric space velocity of the reaction of 1-20 hr ^-1 , The total molar ratio of hydrogen to diolefin is 0.1-5.0; Preferably, the reaction conditions include: the reaction temperature is 50-200°C, the reaction pressure is 0.5-1.0 MPa, the liquid hourly volumetric space velocity of the reaction is 5-10hr ^-1 , and the total molar ratio of hydrogen to diolefin is 0.5 -2.0.

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