WO2021110083A1 - Catalyst suitable for hydrocarbon conversion reaction, preparation method therefor and application thereof - Google Patents

Abstract

A catalyst, comprising: a carrier, the carrier comprising a first carrier and a second carrier coated at the outer surface of the first carrier; and a catalytically active component supported on the second carrier, wherein the first carrier has a porosity that is smaller than or equal to 35%, the ratio of the thickness of the second carrier to the effective diameter of the first carrier is between 0.01 and 0.2, and a pore distribution curve of the second carrier has two pore distribution peaks; and the pore diameter corresponding to the peak value of a first pore distribution peak falls within a range of 4 to 80 nm, and the pore diameter corresponding to the peak value of a second pore distribution peak falls within the range of 100 to 8000 nm. The catalyst has outstanding selectivity and activity in long-chain hydrocarbon conversion reactions. At the same time, the catalyst has good stability, and may significantly improve selectivity, reduce side reactions, and prolong the service life of the catalyst.

Description

Catalyst suitable for hydrocarbon conversion reaction, its preparation method and application

Cross-references to related applications

This application claims the priority of the patent application filed on December 3, 2019, with application number 201911222509.X, titled "a catalyst for hydrocarbon conversion reaction", the content of which is incorporated herein by reference in its entirety.

Technical field

This application relates to the technical field of catalytic reactions, in particular to a catalyst that can be used to catalyze hydrocarbon conversion reactions, and a preparation method and application thereof.

Background technique

The hydrocarbon conversion process of _{long-chain hydrocarbons, especially C 10} -C ₁₅ long-chain hydrocarbons, is involved in the production of synthetic detergents and various surfactants.

There are many patents for catalysts used in the conversion of long-chain alkanes/olefins, such as dehydrogenation of long-chain alkanes, selective hydrogenation of long-chain diolefins, and alkylation of long-chain alkanes/olefins. Most of these catalysts use porous activated alumina as the carrier, with Group VIII metals as the main catalytic element. For long-chain alkanes dehydrogenation reactions, platinum is often used as the first catalytically active component, tin is used as the second catalytically active component, and alkali metals or alkaline earth metals are used as the third catalytically active component.

US Patent No. 4,551,574 discloses a catalyst for the dehydrogenation of hydrocarbons. The porous carrier of the catalyst is uniformly distributed with platinum group components, tin components, indium components, alkali metal or alkaline earth metal components, wherein the indium component The atomic ratio with platinum group components is greater than 1.0. The catalyst can be used in particular for the _{dehydrogenation of C 10} -C ₁₅ paraffins to olefins.

Chinese patent application CN101612583A discloses an activity for the dehydrogenation of saturated hydrocarbons such as C ₃ -C ₂₀ alkanes and alkyl aromatics, especially suitable for the dehydrogenation of C ₁₀ -C ₁₅ long linear alkanes to monoolefins. Saturated alkane dehydrogenation catalyst with heterogeneous distribution of components. Among them, the distribution of catalyst active components on the surface of the carrier can shorten the reaction diffusion path and improve the selectivity and stability of the reaction. The catalyst uses alumina pellets as the carrier, and uses the impregnation method to load various catalytically active components on the carrier non-uniformly. Among them, platinum metal as the active component is mainly distributed on the surface of the carrier, tin, basic metals and group VIII metals As an auxiliary agent, the whole is evenly distributed in the carrier.

Chinese patent CN1018619B discloses a surface-impregnated dehydrogenation catalyst particle. This system includes a catalyst particle, which contains a platinum group metal component, and a promoter metal selected from tin, germanium, rhenium and mixtures thereof The component, an optional alkali metal or alkaline earth metal or a mixture component thereof and an optional halogen component, are supported on a solid heat-resistant oxide support with a nominal equivalent diameter of at least 850 μm. This new catalyst system is particularly useful as a hydrocarbon dehydrogenation catalyst. The patent believes that all the catalytically active components impregnated on the surface are confined to the 400μm deep shell layer on the outer surface of the catalyst carrier, and its catalytic sites are more accessible, making the hydrocarbon reactants and products have a shorter diffusion path. By improving the diffusion path, the residence time of reactants and products in the catalyst particles is shortened, thereby reducing undesirable side effects due to secondary reactions.

Hydrocarbons enter the pores of the catalyst during the hydrocarbon conversion process, and a series of reactions occur on the surface of the active center. Compared with short-chain hydrocarbons, long-chain hydrocarbons have a longer carbon chain, so their mass transfer resistance in the pores of the catalyst is large, the residence time is long, and deep side reactions are prone to occur, which reduces the selectivity of the hydrocarbon conversion process and also makes the catalyst The life span is shorter. The above-reported technologies use different methods to reduce the occurrence of side reactions, but the effect is still not satisfactory.

Summary of the invention

The purpose of this application is to provide a catalyst with a novel structure and a preparation method and application thereof. The catalyst can overcome the large mass transfer resistance and selectivity of the prior art catalyst in the hydrocarbon conversion reaction involving macromolecular long-chain alkanes/olefins. The problem of low catalyst life and short catalyst life, while improving the utilization efficiency of catalytically active components in the catalyst.

In order to achieve the above objective, on one hand, the present application provides a catalyst, including a carrier, the carrier includes a first carrier and a second carrier coated on the outer surface of the first carrier, and a catalyst supported on the second carrier. A catalytically active component, wherein the porosity of the first carrier is ≤ 35%, the ratio of the thickness of the second carrier to the effective diameter of the first carrier is between 0.01-0.2, and the pores of the second carrier The distribution curve 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, and the pore diameter corresponding to the peak of the second pore distribution peak is in the range of 100-8000 nm.

On the other hand, this application provides a method for preparing a catalyst, which includes 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.

In another aspect, the present application provides the use of the catalyst according to the present application or the catalyst prepared by the method of the present application for catalyzing the conversion reaction of hydrocarbons.

In another aspect, the present application provides a method for catalytic conversion of hydrocarbons, including the step of contacting and reacting a hydrocarbon feedstock with a catalyst according to the present application or a catalyst prepared by the method of the present application.

Preferably, the hydrocarbons include C ₃ -C ₂₀ alkanes or alkenes, more preferably C ₁₀ -C ₁₅ linear alkanes or alkenes.

Preferably, the conversion reaction is selected from dehydrogenation, alkylation and hydrogenation reactions.

This application selects different substances to form a catalyst carrier that contains a first carrier and a second carrier coated on the outer surface of the first carrier. The catalytic reaction active centers are distributed on the second carrier in the outer layer, which greatly shortens The diffusion distance between the reactant and the product in the catalyst is determined. 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 of 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 recovery from the spent catalyst after the catalyst is deactivated and replaced. The difficulty of precious metals also reduces the diffusion of reactants and products into the first carrier and 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.

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

The application will be further described in detail below through specific implementations. It should be understood that the specific implementations described here are only used to illustrate and explain the application, but do not limit the application 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 based on the quality of the corresponding carrier and can be measured by 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 embodiment described herein can be freely combined with one or more other embodiments described herein, and the technical solutions or technical ideas formed thereby shall be regarded as part of the original disclosure or original record of this application, 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, in the first aspect, the present application provides a catalyst including a carrier, the carrier including a first carrier and a second carrier coated on the outer surface of the first carrier, and supported on the second carrier The catalytically active component, wherein the porosity of the first carrier is less than or equal to 35%, the ratio of the thickness of the second carrier to the effective diameter of the first carrier is between 0.01-0.2, and the second carrier’s The pore distribution curve has two pore distribution peaks, where the pore size corresponding to the peak of the first pore distribution peak (also called the maximum value of the pore size distribution of the first type of pore) is in the range of 4-80 nm, and the second pore distribution peak is The peak (also referred to as the maximum value of the pore size distribution of the second type of pore) corresponds to the pore size in the range of 100-8000 nm.

The catalyst of 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.}

The low-porosity first carrier of the present application reduces the infiltration of catalytically active components, and its precious metal content is extremely low, which improves the utilization efficiency of catalytically active components. 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.

In addition, the use of the low-porosity first support also reduces the difficulty of recovering precious metals from spent catalysts. For catalysts containing platinum 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 acids or alkalis to dissolve the spent catalysts 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 of the present 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, The infiltration of catalytically active components is reduced, and the amount of precious metals contained in the first carrier is minimized, thereby reducing the loss when recovering precious metals from the spent catalyst.

According to the present application, the pores corresponding to the first pore distribution peak, that is, the first type of pores, generally have a pore diameter in the range of 4-200 nm, preferably in the range of 6-100 nm; and the second pore distribution The pores corresponding to the peaks, 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 is in the range of 8-50 nm, 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 200-3000 nm. Within the range, more preferably within 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 (also referred to as the total specific pore volume of the first type of pore and the second type of pore) It 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.

The catalyst according to the present application is suitable for catalyzing the conversion reaction of hydrocarbons. The hydrocarbons may include C ₃ -C ₂₀ alkanes or alkenes, preferably C ₁₀ -C ₁₅ long linear alkanes or alkenes; the conversion reaction may include desulfurization. Hydrogen, alkylation and hydrogenation reactions.

Long-chain alkanes/alkenes, especially C ₁₀ -C ₁₅ straight-chain alkanes/alkenes, have relatively large molecules. Compared with some small molecular hydrocarbons with low carbon numbers, long-chain alkanes/olefins 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. , Short service life. The carrier of the catalyst of this application is composed of the combination of the first carrier and the second carrier with two different properties. The catalytic reaction active center is only distributed on the second carrier in the outer layer, which greatly reduces the diffusion of reactants and products in the catalyst. distance. The second support can provide two different types of pores. The first type of pores has a smaller size (the maximum pore size distribution is between 4 and 80 nm), which provides the high specific surface area and active centers required for the reaction, making the catalyst The reaction activity is improved; the second type of pore has a larger size (the maximum pore size distribution is between 100-8000nm) as a diffusion channel for reactants and products, which greatly reduces the diffusion time of reactants and products, and improves the reaction During the diffusion process of the product and the product, the diffusion resistance of the reactant and the product 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 and accumulation of carbon deposits are improved, and the service life of the catalyst is prolonged. Therefore, the catalyst of the present application is particularly suitable for the hydrocarbon conversion process of long-chain alkanes/olefins, such as dehydrogenation of long-chain alkanes, selective hydrogenation of long-chain diolefins, alkylation of long-chain olefins, etc., such as C _3- hydrocarbon conversion processes C ₂₀ alkanes and alkenes, in particular linear C ₁₀ -C ₁₅ long-chain alkane dehydrogenation Preparation monoolefins, C ₁₀ -C ₁₅ long-chain diolefin selective hydrogenation, C ₁₀ -C ₁₅ long chain Processes such as the alkylation of olefins.

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.

According to the present application, the thickness of the second carrier is determined according to the effective diameter of the first carrier, thereby obtaining the best catalytic reaction performance, usually the ratio of the thickness of the second carrier to the effective diameter of the first carrier Between 0.01-0.2.

In a preferred embodiment, the catalytically active component of the catalyst of the present application includes a first catalytically active component, a second catalytically active component, and a third catalytically active component, and the first catalytically active component includes one or A variety of metals selected from the platinum group metals, such as platinum, palladium, osmium, iridium, ruthenium, rhodium, or mixtures thereof, preferably platinum; the second catalytically active component includes one or more selected from the group IIIA, the third Metals of group IVA, group IIB and transition metals are preferably selected from tin, germanium, lead, indium, lanthanum, cerium, zinc or mixtures thereof, more preferably selected from tin and lanthanum, particularly preferably tin; the third catalytic activity The components include one or more metals selected from alkali metals and alkaline earth metals, preferably selected from lithium, sodium, potassium, magnesium, calcium, strontium or a combination thereof, more preferably selected from sodium and magnesium, particularly preferably sodium. Further preferably, based on the total weight of the catalyst, the catalyst comprises 0.05-0.5wt% of the first catalytically active component, 0.01-0.5wt% of the second catalytically active component and 0.01-0.5wt% of the first catalytically active component. Three catalytically active components.

In a further preferred embodiment, the first catalytically active component is platinum, the second catalytically active component is tin, and the third catalytically active component is an alkali metal, such as lithium, sodium and/or potassium. , Preferably sodium. More preferably, based on the total weight of the catalyst, the catalyst contains 0.05-0.5% by weight of platinum, 0.01-0.5% by weight of tin, and 0.01-0.5% by weight of alkali metals.

In a further preferred embodiment, the catalytically active component further includes a fourth catalytically active component, and the fourth catalytically active component includes one or more selected from the group consisting of iron, cobalt and nickel, preferably cobalt. Based on the total weight of the catalyst, the content of the fourth catalytically active component is 0.01-1.5 wt%. More preferably, based on the total weight of the catalyst, the catalyst comprises 0.05-0.5wt% platinum; 0.01-0.5wt% tin; 0.01-0.5wt% alkali metals (such as lithium, sodium and/or Potassium, preferably sodium); and 0.01-1.5 wt% cobalt.

According to the present application, the catalyst performance can be adjusted by adjusting the atomic ratio of tin and platinum in the catalytically active component, where the atomic ratio of tin and platinum is generally 1-5, preferably 1-2.

In the second aspect, the present application provides a method for preparing a catalyst, which includes 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 forming of the first carrier can be based on the characteristics of the constituent materials by selecting carrier forming 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 coating the resulting slurry on the outer surface of the first carrier by conventional methods such as dipping, spraying, coating, etc. , 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.

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. The carrier impregnated with catalytically active components is dried in an environment of 80-150°C, and then roasted at a constant temperature of 250-650°C for 2-8 hours, and steamed at 200-700°C for further treatment for 0.5-4 hours, and then heated at 100°C. Reduce with hydrogen at -600°C for 0.5-10 hours to obtain a catalyst product.

In the third aspect, the present application provides the use of the catalyst according to the present application or the catalyst prepared by the method of the present application for catalyzing the conversion reaction of hydrocarbons.

In a fourth aspect, the present application provides a method for catalytic conversion of hydrocarbons, including the step of contacting and reacting a hydrocarbon feedstock with a catalyst according to the present application or a catalyst prepared by the method of the present application.

In a preferred embodiment, the hydrocarbons include C ₃ -C ₂₀ alkanes or alkenes, more preferably C ₁₀ -C ₁₅ linear alkanes or alkenes.

In a preferred embodiment, the conversion reaction is selected from dehydrogenation, alkylation and hydrogenation reactions.

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

1. A catalyst for hydrocarbon conversion reaction, characterized in that the catalyst comprises a carrier and at least one catalytic component supported on the carrier, and the carrier comprises at least one first layer carrier and one The second layer of carrier, the second layer of carrier encapsulates the first layer of carrier from space, the material of the first layer of carrier is different from the material of the second layer of carrier, and the second layer of carrier is deposited on The ratio of the thickness of the second layer carrier to the effective diameter of the first layer carrier is between 0.01-0.2, and the second layer carrier is distributed with the first type of pores and For the second type of holes, the maximum value of the pore size distribution of the first type of holes is between 4-50 nm, and the maximum value of the pore size distribution of the second type of holes is between 100-1000 nm.

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

3. The catalyst according to item 1, characterized in that the porosity of the first layer of support is less than the porosity of the second layer of support, the pore volume of the first layer of support ≤ 0.3ml/g, BET The specific surface area is less than or equal to 20m ² /g.

4. The catalyst according to item 1, wherein the catalytic component comprises one or more first catalytic components, one or more second catalytic components, and one or more third catalytic components. The catalytic component, the first catalytic component includes one or more platinum group metals, the second catalytic component includes one or more group IIIA, group IVA, group IIB, transition metals, so The third catalytic component includes one or more alkali metals and alkaline earth metals.

5. The catalyst according to item 4, characterized in that the first catalytic component is platinum, the second catalytic component is tin, and the third catalytic component is an alkali metal.

6. The catalyst according to item 5, characterized in that the weight percentage of the catalytic component to the total weight of the catalyst is: platinum 0.05-0.5%; tin 0.01-0.5%; alkali metal 0.01-0.5%.

7. The catalyst according to item 4, characterized in that the third catalytic component further includes one or more of iron, cobalt, and nickel, which accounts for 0.01-1.5% by weight of the total weight of the catalyst .

8. The catalyst according to item 7, characterized in that the third catalytic component is cobalt.

9. The catalyst according to item 1, characterized in that the hydrocarbons include C ₃ -C ₂₀ alkanes, preferably C ₁₀ -C ₁₅ long linear alkanes or alkenes, and the conversion reaction includes dehydrogenation, alkanes Base and hydrogenation.

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.

Weigh 0.44g of tin tetrachloride pentahydrate and 0.58g of sodium chloride respectively, and dissolve them in 32ml of chloroplatinic acid aqueous solution with a concentration of 6.5mg/ml in terms of platinum, add 10ml of hydrochloric acid with a concentration of 15wt%, and then use distilled water Dilute to 75ml to obtain an immersion liquid. Take 100g of the prepared carrier and immerse it in the dipping solution, immerse it for 10 minutes to fully absorb it, then heat and vacuum until there is no liquid residue, dry at 120°C for 0.5 hours, and then calcinate at 450°C for 4 hours, and pass water at 450°C. Steam treatment for 1 hour, and reduction with hydrogen at 500° C. for 2 hours to prepare a finished catalyst A. Measured by X-ray fluorescence spectrometry, based on the total mass of the catalyst, catalyst A contains 0.21 wt% platinum, 0.15 wt% tin, and 0.23 wt% sodium.

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.

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.

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.

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 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.

Refer to the method of Example 3 to prepare 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 180 μm, and the ratio to the diameter of the first carrier was 0.09.

Weigh 0.44g of tin tetrachloride pentahydrate, 0.58g of sodium chloride and 0.44g of cobalt chloride hexahydrate, respectively, and dissolve them in 32ml of chloroplatinic acid aqueous solution with a concentration of 6.5mg/ml in terms of platinum, and add 10ml to a concentration of 15wt % Hydrochloric acid, and then diluted with distilled water to 75ml to obtain an immersion liquid. Take 100g of the prepared carrier and immerse it in the dipping solution, immerse it for 10 minutes to fully absorb it, then heat and vacuum until there is no liquid residue, dry at 120°C for 0.5 hours, then calcinate at 450°C for 4 hours, and pass at 450°C. Treated with steam for 1 hour, and reduced with hydrogen at 500°C for 2 hours to prepare a finished catalyst E. Measured by X-ray fluorescence spectroscopy, based on the total mass of the catalyst, catalyst E contained 0.21 wt% platinum, 0.15 wt% tin, 0.23 wt% sodium, and 0.11 wt% cobalt.

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 16 nm, and the maximum value of the pore size distribution of the second type of pore is 630 nm. Based on the mass of the second carrier, the specific pore volume of the first type is 0.89ml/g, the specific pore volume of the second type is 0.68ml/g, and the total specific pore volume is 1.57ml/g. The specific surface area of the second carrier measured by mercury intrusion method was 140 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, 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 catalyst F was obtained according to the catalyst preparation method of Example 1.

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 7 Preparation of Catalyst G

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 (having one type of pores, and 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 G was obtained according to the catalyst preparation method of Example 1.

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 H

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 H was obtained according to the catalyst preparation method of Example 1.

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 I

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 I was obtained according to the catalyst preparation method of Example 1.

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 J

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 J was obtained according to the catalyst preparation method of Example 1.

The catalyst J 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 pore was 19nm, the specific pore volume of the first type was 0.90ml/g, and the second type of pores The maximum pore size distribution is 380nm, the specific pore volume of the second type of pore is 0.74ml/g, and the total specific pore volume is 1.64ml/g. The specific surface area of the carrier measured by mercury intrusion method is 163 m ² /g. Using XRD measurement, the crystal form of the support is γ-alumina.

Comparative Example 4 Preparation of Catalyst K

In this example, alumina powder with two types of pores was used to prepare the second carrier, and mullite was 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 K was obtained according to the catalyst preparation method of Example 1.

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 8 Analysis of Pt 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 Pt 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 Pt content in the first carrier was 0.0011 wt%.

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

The catalyst H obtained in Comparative Example 1 was digested with 15 wt% hydrochloric acid to remove the second carrier, and the Pt 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 Pt content in the first carrier was 0.016wt%.

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 8, it can be seen that after acid cooking, the content of Pt remaining in the catalyst A with low porosity of the first carrier is 0.0011wt% much less than the porosity of the first carrier. The residual Pt content in the high catalyst H is 0.016wt%. The above results indicate that the low-porosity first support of catalyst A reduces the entry of Pt, so that catalyst A has a higher recovery rate of Pt, the use efficiency of precious metals is higher, and the use cost of the catalyst is lower.

Example 9 Dehydrogenation reaction of long-chain alkanes

The catalysts of Examples 1-7 and Comparative Examples 1-4 were tested for the dehydrogenation reaction of long-chain alkanes. The reactor is a stainless steel reaction tube with an inner diameter of 30 mm, with 5 ml of catalyst inside. The raw materials for the reaction are long linear alkanes, of which the total mass content of normal alkanes is 99.73%, of which C ₁₀ component accounts for 9.25%, C ₁₁ component accounts for 29.33%, C ₁₂ component accounts for 30.10%, and C ₁₃ component accounts for 26.52. %, C ₁₄ component accounts for 4.31%, C ₁₅ component accounts for 0.22%, the mass content of non-normal alkane is 0.27%, the reaction temperature is 485℃, the liquid hourly volumetric space velocity is 20h ^-1 , the H ₂ /hydrocarbon molar ratio is 6, the reaction The pressure is 0.1MPa. The reaction raw material mixture is reacted through the catalyst bed under a continuous constant flow under the reaction conditions to obtain a reaction product, which contains the product monoolefin and other by-products, as well as the unreacted raw long-chain alkanes.

The conversion rate and selectivity results of the long-chain alkanes dehydrogenation reaction of the catalysts obtained in each example and comparative example are listed in Table 1 and Table 2, respectively, where the conversion rate of long-chain alkanes = (mass content of long-chain alkanes in the raw material -The mass content of long linear alkanes in the product)/the mass content of long linear alkanes in the raw material*100%, monoolefin product selectivity = the mass content of monoolefins in the product/(the mass content of long linear alkanes in the raw material- The mass content of long linear alkanes in the product)*100%.

Table 1 Conversion rate of catalytic dehydrogenation reaction

Table 2 Mono-ene selectivity in catalytic dehydrogenation reaction

It can be seen from the data in Table 1 and Table 2 that the seven catalysts A, B, C, D, E, F, and G prepared in Examples 1-7 of the present application with two-layer supports and two types of pore distributions are compared with those of the catalysts A, B, C, D, E, F, and G. Proportional catalysts I, J, the conversion rate and selectivity of the reaction are significantly improved, of which the conversion rate of catalyst E prepared by adding metal Co has the smallest decrease with time, and the stability and selectivity are better than those of catalysts A and B without adding Co. , C, D, F, G. The conversion rate and selectivity of the catalyst A with the first support with low porosity are higher than those of the catalyst H with the first support with 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, F, and G are all higher than those of the second support. The ratio of the thickness to the effective diameter of the first carrier is not between 0.01 and 0.2 for catalyst K.

The reaction activity of the catalyst will gradually decrease with the extension of the reaction time, which is manifested as a decrease in the conversion rate of the catalyst (that is, the conversion rate of long linear alkanes). For economic considerations, generally when the conversion rate of the catalyst is lower than a certain value, the catalyst needs to be replaced. At this time, the time the catalyst has been used can be regarded as the life of the catalyst. Table 3 shows the time that the catalyst has been used when the conversion rate of long linear alkanes is reduced to 11.0%.

Table 3 The life of the catalyst (use time)

catalyst Life (hours) A 295 B 300 C 336 D 245 E 399 F 292 G 250 H 229 I 190 J 210 K 214

It can be seen from the data in Table 3 that the seven catalysts A, B, C, D, E, F, and G of the present application have significantly longer service times than catalysts H, I, J, and K. The catalyst E prepared by adding metal Co has a longer use time than the catalysts A, B, C, D, F, and G without adding Co. The catalyst of the present application is more stable and has a longer life.

The preferred embodiments of the application are described in detail above, but the application is not limited thereto. Within the scope of the technical concept of the present application, a variety of simple modifications can be made to the technical solutions of the present application, including the combination of various technical features in any other suitable manner. These simple modifications and combinations should also be regarded as the content disclosed in the present application. All belong to the protection scope of this application.

Claims (11)

A catalyst includes a carrier, the carrier includes a first carrier 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 first carrier is Porosity ≤ 35%, the ratio of the thickness of the second carrier 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, where the first The pore diameter corresponding to the peak of the pore distribution peak is in the range of 4-80 nm, preferably in the range of 8-50 nm, 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, It is preferably in the range of 200-3000 nm, more preferably in the range of 200-1000 nm. The catalyst according to claim 1, having 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 catalyst according to any one of the preceding claims, having 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 catalyst according to any one of the preceding claims, having 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 catalyst according to any one of the preceding claims, wherein the catalytically active component comprises a first catalytically active component, a second catalytically active component, and a third catalytically active component, the first catalytically active component The active component includes one or more platinum group metals, the second catalytically active component includes one or more metals selected from group IIIA, group IVA, group IIB and transition metals, and the third The catalytically active component includes one or more metals selected from alkali metals and alkaline earth metals; Preferably, the first catalytically active component is platinum, the second catalytically active component is tin, and the third catalytically active component is an alkali metal. The catalyst according to claim 5, wherein based on the total weight of the catalyst, the catalytically active component comprises 0.05-0.5wt% platinum, 0.01-0.5wt% tin and 0.01-0.5wt% alkali metal . The catalyst according to any one of claims 5-6, wherein the catalytically active component further comprises a fourth catalytically active component, the fourth catalytically active component comprising one selected from the group consisting of iron, cobalt and nickel One or more, preferably cobalt, the content of the fourth catalytically active component is 0.01-1.5 wt% based on the total weight of the catalyst. A method for preparing a catalyst includes 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 method according to claim 8, wherein: The drying of step 1) is performed at a temperature of 100-150°C for 2-8 hours, and the roasting of step 1) is performed at a temperature of 350-1700°C for 2-10 hours; The drying of step 2) is carried out at a temperature of 60-200°C for 0.5-10 hours, and the roasting of step 2) is roasted at a temperature of 300-1000°C for 2-15 hours; The coating described in step 2) is performed by a method selected from dipping, spraying and coating; The ratio of the thickness of the second carrier obtained in step 2) to the effective diameter of the first carrier is between 0.01-0.2; The pore-forming agent used in step 2) is selected from sesame powder, methyl cellulose, polyvinyl alcohol, carbon black or a mixture thereof; The catalytically active component described in step 3) includes a first catalytically active component, a second catalytically active component, and a third catalytically active component, and the first catalytically active component includes one or more platinum groups Metal, the second catalytically active component includes one or more metals selected from group IIIA, group IVA, group IIB and transition metals, and the third catalytically active component includes one or more selected Metals selected from alkali metals and alkaline earth metals; preferably, the first catalytically active component is platinum, the second catalytically active component is tin, and the third catalytically active component is an alkali metal; The drying of step 3) is carried out at a temperature of 80-150°C for 0.5-5 hours, the roasting of step 3) is carried out at a temperature of 250-650°C for 2-8 hours, and the steam treatment of step 3) is carried out at 200-700 0.5-4 hours at a temperature of ℃; and/or The reduction in step 4) is carried out at a temperature of 100-600°C for 0.5-10 hours. The use of the catalyst according to any one of the preceding claims for catalyzing the conversion reaction of hydrocarbons, wherein the hydrocarbons preferably comprise C ₃ -C ₂₀ alkanes or alkenes, more preferably C ₁₀ -C ₁₅ linear For alkanes or alkenes, the conversion reaction is preferably selected from dehydrogenation, alkylation and hydrogenation reactions. A method for catalytic conversion of hydrocarbons, comprising the step of contacting a hydrocarbon feedstock with the catalyst according to any one of claims 1-7, wherein the hydrocarbons preferably include C ₃ -C ₂₀ alkanes or alkenes, more preferably C _{10 to} C ₁₅ linear alkanes or alkenes, the conversion reaction is preferably selected from dehydrogenation, alkylation and hydrogenation reactions.

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