CN108855057B

CN108855057B - Shell layer distribution type catalyst, preparation method thereof and Fischer-Tropsch synthesis method

Info

Publication number: CN108855057B
Application number: CN201710344084.4A
Authority: CN
Inventors: 孙霞; 侯朝鹏; 夏国富; 吴玉; 晋超; 阎振楠; 李明丰; 吴昊
Original assignee: Sinopec Research Institute of Petroleum Processing; China Petroleum and Chemical Corp
Current assignee: Sinopec Research Institute of Petroleum Processing; China Petroleum and Chemical Corp
Priority date: 2017-05-16
Filing date: 2017-05-16
Publication date: 2021-01-08
Anticipated expiration: 2037-05-16
Also published as: CN108855057A

Abstract

The invention relates to the field of catalyst preparation, and discloses a shell-distributed catalyst, a preparation method thereof and a Fischer-Tropsch synthesis method, wherein the preparation method of the catalyst comprises the following steps: placing a porous carrier in a hollow rotary drum body, spraying a solution containing a catalytic active component on the surface of the porous carrier, wherein the total spraying amount of the solution is less than the total pore volume of the porous carrier, the rotary drum body is provided with an openable feed inlet for receiving the porous carrier and an openable discharge outlet for outputting the porous carrier, the ratio of the axial length to the radial maximum length of the rotary drum body is 3-9, the rotary drum body is horizontally arranged, the porous carrier loaded with the solution leaves the rotary drum body through the discharge outlet, then the porous carrier is supplemented into the rotary drum body through the feed inlet, and the porous carrier leaving the middle container is dried and optionally roasted. The catalyst prepared by the method has high shell rate, high strength and high forming rate, and is more beneficial to detecting the product quality.

Description

Shell layer distribution type catalyst, preparation method thereof and Fischer-Tropsch synthesis method

Technical Field

The invention relates to the field of catalyst preparation, in particular to a shell-distributed catalyst and a preparation method thereof, and also relates to a Fischer-Tropsch synthesis method.

Background

If the product molecules generated by the reaction at the deep part of the catalyst pore channel can not be diffused out in time to further react, the selectivity of the catalyst is influenced on one hand, and the service life of the catalyst is influenced on the other hand. Particularly reactions in which internal diffusion is a controlled step, it is desirable that the reaction occur at a site that facilitates diffusion of the reactants and products, and generally at the surface of the catalyst. In addition, in the cost of the catalyst, the proportion of the cost of the active component is larger, and if the component which is not high in utilization rate and distributed in the deep part of the pore channel is moved to the area close to the surface layer of the catalyst, the cost of the catalyst is undoubtedly reduced, and the activity and the selectivity of the catalyst are favorably improved.

For gas-solid-liquid heterogeneous reaction systems such as fischer-tropsch (FT) synthesis carried out in fixed bed reactors, the catalyst particle size is typically a few mm, and therefore the effect of diffusion control on catalytic activity is difficult to avoid. It is noted that: the heavy paraffin synthesized by FT is usually attached to the catalyst surface in the form of liquid, sol or slurry, and reacts with the reactant H₂And the diffusion of CO inside the catalyst particles. During the internal diffusion of the reactants, H₂Has a diffusion speed higher than that of CO, and the diffusion limiting effect of CO in the catalyst particles is obviously stronger than that of H₂. Due to different particle sizes of the particles, the interior of the particles is formedThe difference of CO concentration gradient influences the combination of CO and the active center position of metal, so that the H/C ratio adsorbed on the active center is increased, the carbon chain growth probability is reduced, and the C is reduced₅₊Selectivity of (2). The prior art shows that catalysts having a non-uniform distribution of active components, such as shell distributed catalysts (i.e., shell catalysts or eggshell catalysts), can significantly increase C in reactions such as fischer-tropsch synthesis due to low diffusion limitations relative to catalysts having a uniform distribution of active components₅₊Selectivity, reduces the selectivity of methane, and is more suitable for Fischer-Tropsch synthesis reaction.

US5545674 discloses a process for the preparation of shell distributed catalysts by repeated impregnation of cobalt, especially cobalt nitrate solutions, onto a particulate support using an immersion or spray process with an intermediate drying or burning step. These methods are cumbersome and time consuming and, with multiple impregnation methods, some of the metal penetrates into the support beyond the desired outer layer.

CN101318133A discloses a shell catalyst for preparing naphtha and diesel oil, which uses active carbon as carrier, sprays the solution onto the rolling carrier by spraying, and then dries or calcines the catalyst in inert gas. However, the catalyst prepared by this method has a low shell fraction.

CN102451722A discloses a preparation method of an eggshell type hydrogenation catalyst. The method comprises the steps of impregnating a carrier with an active metal aqueous solution containing a thickening agent and an active metal dispersing agent, wherein the carrier is impregnated under the condition of introducing air bubbles, and then drying and roasting are carried out to obtain the eggshell type hydrogenation catalyst. The method can effectively adjust the surface activity of the eggshell type hydrogenation catalyst, the thickness of the metal shell layer and the dispersion degree of the active metal, stabilize the active metal component on the hydrogenation catalyst, reduce the loss of the active metal component and reduce the production cost of the catalyst. However, this preparation method is time-critical and cumbersome to operate.

CN204911534U discloses an impregnation system, which comprises an impregnation liquid supply unit for supplying impregnation liquid to the impregnation unit, a porous carrier supply unit for supplying porous carrier to the impregnation unit, an impregnation unit for contacting the impregnation liquid with the porous carrier, a vacuum unit for drying the impregnated porous carrier, and a drying unit for drying the porous carrier, wherein the impregnation unit comprises an impregnation drum, the axis of the drum body (301) of the impregnation drum is inclined with respect to the horizontal plane, so that the inlet (302) is located at one end of the higher axial direction, the outlet (303) is located at the other end of the lower axial direction, and the vacuum line (305) is communicated with the vacuum unit. In order to realize continuous operation, the dipping drum needs to be arranged obliquely. In the continuous operation process, if a certain member in the dipping rotary drum is aged or loses efficacy and the product quality is influenced, unqualified products can be continuously produced, and the unqualified product where the production starts cannot be effectively distinguished, so that the quality of the stable product is not good. CN204503105U discloses an impregnation drum, which comprises a hollow drum body (301) for carrying porous carriers, wherein at least one openable and closable material opening for receiving and/or outputting the porous carriers is arranged on the drum body (301), a spray rod (303) is arranged in the drum body (301), at least one atomizing nozzle for spraying impregnation liquid on the surfaces of the porous carriers is arranged on the spray rod (303), a vacuum-pumping pipeline (304) for performing vacuum-pumping is arranged in the drum body (301), the vacuum-pumping pipeline (304) is arranged close to the inner wall of the drum body (301) for carrying the porous carriers, and the distance between the vacuum-pumping pipeline (304) and the inner wall of the drum body (301) for carrying the porous carriers is enough to enable the air-pumping opening on the vacuum-pumping pipeline (304) to be buried in a layer formed by the porous carriers, it is further disclosed that the drum body (301) is conical or biconical sharing the same conical bottom surface. However, when the impregnation drum is used for preparing the catalyst, the strength of the catalyst is poor and the molding rate is low.

Thus, there remains a need to continue to explore methods for preparing shell distributed catalysts.

Disclosure of Invention

The invention aims to provide a shell-distributed catalyst and a preparation method thereof, and the catalyst prepared by the method has high shell rate, high catalyst strength and high forming rate and is more beneficial to detecting the product quality.

The inventor of the invention finds in the research process that the existing preparation shell distribution type catalyst mostly adopts an impregnation drum comprising a conical drum body or an impregnation drum comprising an inclined drum body, the ratio of the axial length to the radial maximum length of the existing conical drum body is basically less than 1, in the impregnation drum provided by the prior art, the drum body is generally 10-15m in length, while the radial diameter of the drum is set to be about 1m, namely, the ratio of the axial length to the radial maximum length of the rotary drum body is more than 10, the centrifugal force of the materials in the rotating process of the existing dipping rotary drum adopting the conical rotary drum body is larger, the strength and the molding rate of the prepared catalyst are greatly reduced, when the ratio of the axial length to the radial maximum length of the rotary drum body provided by the prior art is too large, the impregnation of active components is not facilitated, and the preparation of a catalyst with a high shell rate is not facilitated; in addition, in the prior art, the dipping rotary drums are arranged in an inclined manner to realize continuous operation, and the inventor of the invention finds that in the continuous operation process, if a certain component in the dipping rotary drum is aged or fails to work, so that the product quality is influenced, unqualified products can be continuously produced, and the unqualified product where the production starts cannot be effectively distinguished, so that the stable product quality is not good. And the intermittent operation is adopted, so that the product quality can be monitored more favorably, and when a batch of materials has problems, the materials can be remedied in time. The inventor of the invention further researches and discovers that the drum body with the ratio of the axial length to the radial maximum length of 3-9 is adopted and horizontally arranged, so that the prepared catalyst has higher shell rate, the strength and the forming rate of the catalyst are greatly improved, the product quality can be monitored, and when one batch of materials has problems, the repair can be timely carried out.

In view of this, according to a first aspect of the present invention, there is provided a method for preparing a shell-distributed catalyst, the method comprising:

placing a porous carrier in a hollow rotary drum body, spraying a solution containing a catalytic active component on the surface of the porous carrier, wherein the total spraying amount of the solution is less than the total pore volume of the porous carrier, the rotary drum body is provided with an openable feed inlet for receiving the porous carrier and an openable discharge outlet for outputting the porous carrier, the ratio of the axial length to the radial maximum length of the rotary drum body is 3-9, the rotary drum body is horizontally arranged, the porous carrier loaded with the solution leaves the rotary drum body through the discharge outlet, then the porous carrier is supplemented into the rotary drum body through the feed inlet, and the porous carrier leaving the middle container is dried and optionally roasted.

According to a second aspect of the invention, there is provided a shell distributed catalyst prepared by the process of the invention.

According to a third aspect of the invention, the invention provides a Fischer-Tropsch synthesis method, which comprises the step of contacting synthesis gas with a catalyst under Fischer-Tropsch synthesis reaction conditions, wherein the catalyst is a shell layer distribution type catalyst which is prepared by the method and has a catalytic effect on the Fischer-Tropsch synthesis reaction.

Under the preferable condition of the invention, the ratio of the axial length to the radial maximum length of the rotary drum body is controlled to be 3-5, the material raising plate which is a flaky bulge and the rotating speed of the rotary drum body are controlled to be 3.5-4.5 revolutions per minute, so that the shell-layer distribution type catalyst with higher shell layer rate can be obtained, the strength and the forming rate of the prepared catalyst are further improved, and under the further preferable condition, the performance of the prepared shell-layer distribution type catalyst can be further improved by limiting the rotary drum body to be ellipsoidal. The inventor of the invention discovers in the research process that the ratio of the axial length to the radial maximum length is limited to be 3-5, the material raising plate is limited to be a flaky bulge, the rotating speed of the rotary drum body is 3.5-4.5 revolutions per minute, and the rotary drum body is in an ellipsoidal shape, so that the carrier in the rotary drum body can have more surface area contacting with the impregnation liquid in the movement process (which can be obtained by installing a camera device at a proper position in the device and calculating through the relative relation of the covering areas of the material raising plate on the reference rotary drum and the material in the movement process), the preparation efficiency of the catalyst is further improved, the impregnation effect of the porous carrier is ensured, the shell-type catalyst can be prepared more efficiently, the mechanical strength of the catalyst is reduced as much as possible, and the preparation of the shell-type catalyst is more facilitated.

According to the preparation method of the shell-distributed catalyst, the operation process is simple and easy to control. In addition, according to the preparation method of the shell-layer distribution type catalyst, in the preparation process, the porous carrier loaded with the solution leaves the rotary drum body, and then the porous carrier is supplemented into the rotary drum body, so that the preparation of the shell-layer distribution type catalyst is carried out intermittently, the product quality can be monitored, and when one batch of materials has problems, the problem can be remedied in time. The catalyst prepared by the preparation method of the shell-distributed catalyst provided by the invention has high shell rate, high strength and high forming rate.

The shell-distributed catalyst prepared by the method of the invention is used as the catalyst of the Fischer-Tropsch synthesis reaction, and can obtain higher C₅₊Hydrocarbon selectivity and lower methane selectivity.

Drawings

The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention and not to limit the invention.

FIG. 1 is a schematic view of the structure of an apparatus for preparing a shell distribution type catalyst of the present invention.

Fig. 2 is a schematic view for explaining the structure of the material raising plate provided on the inner wall of the drum body.

Description of the reference numerals

101: porous carrier reservoir 201: solution storage tank containing catalytic active component

202: the pump 301: rotary drum body

302: base 303: spray rod

304: the material raising plate 305: rotating shaft

306: power generation section 307: transmission component

308: feed port 309: discharge port

401: drying the belt 402: distributing device

403: shell body

Detailed Description

The endpoints of the ranges and any values disclosed herein are not limited to the precise range or value, and such ranges or values should be understood to encompass values close to those ranges or values. For ranges of values, between the endpoints of each of the ranges and the individual points, and between the individual points may be combined with each other to give one or more new ranges of values, and these ranges of values should be considered as specifically disclosed herein.

In the present invention, "axial direction" and "radial direction" are relative to the drum body, that is, the direction extending along the rotation axis direction of the drum body is an axial direction, and the direction perpendicular to the axial direction is a radial direction, and it should be noted that these terms are only used for illustrating the present invention, and are not used for limiting the present invention. In the present invention, "optional" means that the technical feature connected to "optional" may be included, or the technical feature connected to "optional" may not be included.

According to a first aspect of the present invention, there is provided a method for preparing a shell distributed catalyst, the method comprising:

placing a porous carrier in a hollow rotary drum body, spraying a solution containing a catalytic active component on the surface of the porous carrier, wherein the total spraying amount of the solution is less than the total pore volume of the porous carrier, the rotary drum body is provided with an openable feed inlet for receiving the porous carrier and an openable discharge outlet for outputting the porous carrier, the ratio of the axial length to the radial maximum length of the rotary drum body is 3-9, the rotary drum body is horizontally arranged, the porous carrier loaded with the solution leaves the rotary drum body through the discharge outlet, then the porous carrier is supplemented into the rotary drum body through the feed inlet, and the porous carrier leaving the rotary drum body is dried and optionally roasted.

In the invention, the axial length and the radial maximum length respectively refer to the axial length and the radial maximum length of the inner cavity of the drum body.

According to the method of the present invention, the total sprayed amount of the solution containing the catalytically active component is less than the total pore volume of the porous support. From the viewpoint of further improving the shell fraction of the prepared catalyst, the total spray amount of the solution containing the catalytically active component is V_LThe total pore volume of the porous carrier is V_C，V_L/V_C0.01-0.99; preferably, V_L/V_C0.1-0.8; more preferably, V_L/V_C0.2-0.7; further preferably, V_L/V_C0.2-0.6. In the present invention, V_CIs equal to the mass of the porous support (in grams) multiplied by the water absorption of the porous support (density of water 1 g/cm)³) The water absorption is the amount of water absorbed per unit weight of the carrier. Specifically, the water absorption can be measured by the following method: the carrier (weight is w)₁In grams) with water in a ratio of carrier (by weight) to water (by volume) of 1: 3 for 2 hours, after filtration, the solid is drained and the weight of the drained solid is then weighed (weight is w)₂In grams), the water absorption was calculated from the following formula:

according to the method of the present invention, the solution containing the catalytically active component can be sprayed onto the surface of the porous support by various methods which are conventionally used. Preferably, the solution containing the catalytically active component is sprayed onto the surface of the porous support in the form of atomized droplets. From the viewpoint of further improving the shell fraction of the finally prepared catalyst and the catalytic efficiency, the size of the atomized liquid droplets is preferably in the range of 1 to 600. mu.m, more preferably in the range of 20 to 400. mu.m, still more preferably in the range of 50 to 300. mu.m, still more preferably in the range of 60 to 200. mu.m, such as in the range of 100-200. mu.m. In the present invention, the size of the atomized droplets is measured by a malvern particle size analyzer and is the volume average particle size. During a particular operation, the size of the atomized droplets formed can be adjusted by adjusting the spray pressure.

According to the method, the rotary drum body is provided with a feed inlet for receiving the porous carrier and a discharge outlet for outputting the porous carrier, and the rotary drum body is horizontally arranged. In the invention, the drum body is horizontally arranged, specifically, the axis of the drum body is horizontally arranged relative to the horizontal plane. The drum body of the invention is allowed to have certain unavoidable errors, but the height difference between the higher end and the lower end of the drum body is controlled to be not more than 10 cm.

According to the method of the invention, the porous carrier loaded with the solution leaves the drum body through the discharge port, and then the porous carrier is supplemented into the drum body through the feed port. Adopt this kind of intermittent type formula operation more to be favorable to monitoring product quality, when a batch material goes wrong, can in time overhaul the device. In the prior art, the axis of the rotary drum body is inclined relative to the horizontal plane, the feeding hole is positioned at one axial end of the rotary drum body, the discharging hole is positioned at the other axial end of the rotary drum body, and in the spraying process, the porous carrier loaded with the solution containing the catalytic active component continuously moves towards the discharging hole and finally leaves the rotary drum body, so that the porous carrier can be continuously supplemented into the rotary drum body correspondingly, and continuous operation is realized. From the viewpoint of further improving the uniformity of contact of the solution containing the catalytically active component with the porous support, it is preferable to keep the porous support in motion during the spraying. The movement may be in the form of one or a combination of two or more of vibration, rolling, flipping and sliding. In the actual operation process, the rotary drum body can rotate by taking the axis as the center, so that the porous carrier in the rotary drum body is driven to move. Generally, the rotation speed of the drum body may be 2 to 15 revolutions per minute, preferably 2 to 10 revolutions per minute, and more preferably 3.5 to 4.5 revolutions per minute.

The catalyst preparation method adopts the rotary drum body with the ratio of the axial length to the radial maximum length of 3-9, and the centrifugal force applied to the materials is smaller in the rotation process of the rotary drum body. In the preparation process of the existing shell layer catalyst, the centrifugal force of materials in the rotating process of the dipping rotary drum adopting the conical rotary drum body is larger, if the rotating speed is higher, the centrifugal force borne by the materials is further increased, the strength and the forming rate of the catalyst are not favorably improved, and when the rotating speed is properly increased (such as 9-15 revolutions per minute) in order to further improve the production efficiency, the shell layer rate of the catalyst prepared by the method provided by the invention is higher, and the strength and the forming rate of the catalyst are higher.

The rotational speed of the impregnation drum using the conical drum body is generally less than the rotational speed of the drum body according to the invention.

The inner wall surface of the rotary drum body is preferably provided with the material raising plate, so that when the rotary drum body rotates, the porous carrier can be raised to a certain height under the carrying of the material raising plate, the porous carrier is effectively turned, the solution containing the catalytic active component is sprayed on the surface of the porous carrier more uniformly, and the prepared catalyst has more uniform composition. The material raising plate can be various components capable of realizing the functions.

In a preferred embodiment, the material raising plate 304 is fixed to a protrusion on the inner wall surface of the drum body, as shown in fig. 2. The bulges protrude from the inner wall of the drum body towards the rotating center of the drum body, so that the porous carrier can be lifted to a certain height and then thrown down while the drum body rotates, and the porous carrier is turned over.

According to a preferred embodiment of the invention, the protrusions are sheet-like protrusions, as shown in fig. 2. The inventor of the invention finds that the sheet-shaped bulges have better turning effect than the spiral bulges and the block-shaped bulges adopted in the prior art in the research process. Still further preferably, the edge of the sheet-like projection facing the cavity of the drum body is a smooth curve. The smooth curve may be a regular smooth curve or an irregular smooth curve (for example, may be wavy). From the viewpoint of further improving the flipping effect (flipping efficiency and catalyst yield), as shown in fig. 2, it is most preferable that the edge of the sheet-like projection facing the cavity of the drum body is a circular arc.

If the edges of the flaky bulges facing to the cavity direction of the drum body are provided with edges and corners, the stirring efficiency of the materials to be impregnated can be improved to a certain extent, but the strength and the forming rate of the prepared catalyst are lower.

According to a preferred embodiment of the present invention, the plate-like projections are arranged in the axial direction of the drum body. More preferably, the material lifting plate comprises a plurality of columns of parallel-arranged flaky protrusions, wherein the distance between two adjacent columns is adjustable, so that the material turning frequency of the material to be impregnated can be changed, and the impregnation effect can be further changed.

Specifically, the smaller the distance between two adjacent rows of sheet-like protrusions is, the greater the material turnover frequency is. As a preferable mode, the distance between two adjacent columns of the sheet-like projections is z (z is the straight distance between the right end point of the left sheet-like projection and the left end point of the right sheet-like projection), and 0< z < R, preferably 0< z <0.25R, more preferably 0.1R < z <0.25R, where R is the radius (the radially largest inner radius) of the drum body 301, is satisfied, in order to achieve the best dipping effect.

Specifically, the shape of each sheet-like projection may be the same or different, and the present invention is not particularly limited thereto. Preferably, each sheet-like projection is shaped like a triangle, and in order to ensure the stirring effect, it is further preferred that the chord length of the bottom arc of the radial section is x, and the height of the radial section is y (the distance from the top point of the circular arc to the chord of the bottom arc), wherein: 0.5y x 2.5y, preferably satisfying: x is more than or equal to 1.8y and less than or equal to 2.3y, so that the porous carrier can be lifted and thrown down in time, and the porous carrier can be prevented from being broken, thereby achieving the most preferable dipping effect.

In addition, the arrangement direction of each protrusion may be parallel to the axial direction, but may also be arranged at an angle with the axial direction, or a plurality of protrusions may be arranged in a staggered manner at an angle therebetween, and all of these arrangements are within the scope of the present invention.

The drum body can have various shapes, such as a nearly ellipsoidal shape, a single conical shape or a double conical shape sharing a bottom surface, and can also be an irregular shape without special edges and corners. In a preferred embodiment, as shown in fig. 1, the drum body 301 is ellipsoidal.

According to a preferred embodiment of the invention, the ratio of the axial length to the maximum radial length of the drum body is between 3 and 5. By adopting the preferred embodiment of the invention, the problem that the material is subjected to larger inertia force during the rotation process of the biconical impregnation body (the ratio of the axial length to the radial maximum length is less than 1) sharing the bottom surface in the prior art can be further avoided, and the reduction of the strength and the forming rate of the catalyst can be further avoided. When the ratio of the axial length to the radial maximum length of the drum body is too large, impregnation of active components is not facilitated, and preparation of a catalyst with a high shell rate is not facilitated.

By adopting the most preferred embodiment of the invention, the ratio of the axial length to the radial maximum length of the rotary drum body is 3-5, the rotating speed of the rotary drum body is 3.5-4.5 r/min, the inner wall surface of the rotary drum body is provided with the material raising plates which are limited to be sheet-shaped bulges, and the rotary drum body is in an ellipsoidal shape, so that the porous carrier in the rotary drum body can have more surface areas to contact with the impregnation liquid in the movement process (which can be obtained by installing a camera device at a proper position in the device and calculating by referring to the relative relation of the covering areas of the material raising plates on the rotary drum and the material in the movement process), the preparation of the shell distribution type catalyst is more facilitated, and the strength and the forming rate of the prepared catalyst are higher.

In the present invention, "openable and closable" means that the material opening can have two states of opening and closing. As shown in fig. 1, when the drum body 301 is an ellipsoid, an openable inlet 308 is disposed on an upper dome of the ellipsoid along the radial direction, and an openable outlet 309 is disposed on another dome opposite to the dome where the first inlet 308 is located.

According to the method of the present invention, the temperature inside the drum body during the spraying is not particularly limited and may be performed at a usual temperature. Generally, the temperature within the drum body can be controlled within the range of 0-70 deg.C, preferably 25-50 deg.C, during the spraying process.

According to the process of the present invention, the porous support may be a conventional porous material suitable as a catalyst support. Specifically, the porous carrier may be one or more of a heat-resistant inorganic oxide, aluminum silicate, and activated carbon. The heat-resistant inorganic oxide refers to an inorganic oxygen-containing compound with a decomposition temperature of not less than 300 ℃ (for example, the decomposition temperature is 300-1000 ℃) in oxygen or oxygen-containing atmosphere. Specific examples of the porous carrier may include, but are not limited to: one or more of alumina, silica, titania, magnesia, zirconia, thoria, silica-alumina, aluminum silicate and activated carbon. Preferably, the porous carrier is one or more of silica, alumina, silica-alumina, aluminum silicate, titania, zirconia, and activated carbon. More preferably, the porous support is alumina.

The shape of the carrier in the present invention is not particularly limited, and may be a conventional shape, for example, a sphere, a tablet, a bar, etc., and preferably a bar. According to the process of the present invention, the average particle diameter of the porous support may be selected according to the specific kind of the catalyst, and is preferably in the range of 0.5 to 8mm, more preferably in the range of 2 to 8 mm.

The solvent of the solution containing the catalytically active component may be conventionally selected and may be, for example, one or a mixture of two or more of water, alcohol, ether, aldehyde and ketone. Preferably, the solvent is water and/or an alcohol, such as one or a mixture of two or more of water, methanol and ethanol. From the viewpoint of environmental protection and cost reduction, the solvent is more preferably water.

According to the method of the present invention, the type of the catalytically active component may be selected according to the intended application of the catalyst, so as to obtain a catalyst with predetermined catalytic properties, such as a group VIII metal element and/or a group VIB metal element. In a preferred embodiment of the invention, the catalytically active component is of a type such that the shell distributed catalyst prepared by the process of the invention is catalytic for the fischer-tropsch synthesis reaction. In this preferred embodiment, the catalytically active component may be a component having a catalytic effect on the fischer-tropsch synthesis reaction, and preferably, the catalytically active component is selected from group VIII metal elements, and specifically, may be one or more of iron, cobalt, and ruthenium.

According to the method of the present invention, the solution containing the catalytically active component may be provided by dissolving a compound containing the catalytically active component in a solvent. The kind of the compound containing the catalytically active component may be selected depending on the kind of the solvent, so as to be soluble in the solvent. For example, when the solvent is water, the compound containing a catalytically active component may be a water-soluble compound. In one embodiment of the present invention, when the catalytically active component is a group VIII metal element, the compound containing the catalytically active component may be one or more of a water-soluble nonmetallic oxygen-containing inorganic acid salt having a group VIII metal as a cation, a water-soluble organic acid salt having a group VIII metal as a cation, and a water-soluble halide having a group VIII metal as a cation. Preferably, the compound containing the catalytic active component is one or more of nitrate with the VIII group metal as the cation, acetate with the VIII group metal as the cation, sulfate with the VIII group metal as the cation, basic carbonate with the VIII group metal as the cation and chloride with the VIII group metal as the cation. Specifically, the compound containing a catalytically active component may be selected from one or more of, but not limited to, nickel nitrate, nickel acetate, nickel sulfate, basic nickel carbonate, cobalt nitrate, cobalt acetate, cobalt sulfate, basic cobalt carbonate, cobalt chloride, nickel chloride, ruthenium chloride, and ruthenium nitrate.

The concentration of the catalytically active component in the solution containing the catalytically active component may be selected according to the desired loading amount of the catalytically active component in the catalyst, and is not particularly limited.

According to the method of the present invention, the loading amount of the solution containing the catalytically active component on the porous support is such that it can be ensured that the finally prepared catalyst is loaded with a sufficient amount of the catalytically active component. Generally, the loading of the catalytically active component on the porous support is such that the content of the catalytically active component, calculated as oxide, is from 0.5 to 60% by weight, preferably from 1 to 50% by weight, such as from 10 to 30% by weight, based on the total amount of the finally prepared catalyst.

According to the process of the invention, the solution containing the catalytically active component may also contain at least one catalyst promoter component.

The promoter component may be, for example, elemental phosphorus and/or elemental fluorine. When the catalyst has a catalytic effect on the Fischer-Tropsch synthesis reaction, the catalyst promoter component can be one or more than two selected from Li, Na, K, Mg, Ca, Sr, Cu, Mo, Ta, W, Ru, Zr, Ti, Re, Hf, Ce, Mn, Fe, V and noble metals (such as one or more than two of Pt, Pd, Rh and Ir).

The content of the catalyst promoter component in the solution containing the catalytically active component is based on the content of the catalyst promoter component expected in the finally prepared catalyst. Generally, the promoter-containing component may be present in an amount of 0.1 to 30% by weight, preferably 0.5 to 15% by weight, more preferably 1 to 5% by weight, calculated as the oxide, based on the total amount of the finally prepared catalyst.

According to the method of the present invention, after the spraying is completed, the resulting solution-loaded porous carrier is dried. The drying temperature is based on the solvent which can be removed from the solution loaded on the porous carrier. In general, the drying can be carried out at a temperature of from 50 to 290 ℃ and preferably at a temperature of from 60 to 250 ℃. The drying may be performed under normal pressure or under reduced pressure.

In a preferred embodiment of the present invention, the drying is carried out under normal pressure (i.e., 1 atm), and the temperature of the drying is preferably in the range of 50 to 290 ℃, more preferably in the range of 60 to 250 ℃, and still more preferably in the range of 140 ℃ to 160 ℃. In another preferred embodiment of the present invention, the drying is carried out under a pressure (in gauge) of from-0.5 kPa to-60 kPa, preferably from-5 kPa to-45 kPa, the temperature of the drying being preferably in the range of from 100 ℃ to 220 ℃, more preferably in the range of from 120 ℃ to 160 ℃.

According to the method of the present invention, the duration of the drying may be selected according to the temperature and pressure of the drying so as to be able to remove all or substantially all of the solvent from the solution supported on the porous support. In general, the duration of the drying may be from 1 to 48 hours, preferably from 1.5 to 24 hours, more preferably from 2 to 10 hours, such as from 2 to 5 hours.

According to the method of the present invention, the dried porous carrier can be used as a catalyst directly or after calcination. In the present invention, the conditions for the calcination are not particularly limited and may be selected conventionally. Generally, the calcination may be carried out at a temperature of 300-600 ℃, preferably at a temperature of 400-500 ℃. The duration of the calcination may be 1 to 48 hours, preferably 2 to 12 hours, more preferably 2 to 4 hours.

In a preferred embodiment of the present invention, the process according to the invention is carried out in a preparation system to prepare a shell-distributed catalyst. The preparation system is described in detail below with reference to fig. 1.

The preparation system comprises a solution supply unit containing a catalytic active component, a porous carrier supply unit, an impregnation unit, a vacuum unit and a drying unit, wherein the solution supply unit containing the catalytic active component is used for supplying a solution containing the catalytic active component to the impregnation unit, the porous carrier supply unit is used for supplying a porous carrier to the impregnation unit, the impregnation unit is used for enabling the solution containing the catalytic active component to be in contact with the porous carrier, and the drying unit is used for drying the impregnated porous carrier, wherein the impregnation unit comprises a rotary drum body 301 used for bearing the porous carrier, one radial end of the rotary drum body 301 is provided with a feed inlet 308 used for receiving the porous carrier, and the other radial end of the rotary drum body is provided with a discharge outlet 309 used for outputting the porous carrier. The inlet 308 and outlet 309 are each provided as a hopper with an openable top cover and an openable bottom cover.

As shown in fig. 1, the solution supply unit containing a catalytically active component includes a solution tank 201 containing a catalytically active component and a line for communicating the solution tank 201 containing a catalytically active component with the spray bar 303 in the drum body 301, so that the solution containing a catalytically active component can be continuously fed into the drum body 301. Depending on the particular need, a pump 202 may be placed in the line to increase the efficiency of the delivery, while increasing the pressure of the solution containing the catalytically active component fed into the spray bar 303 to provide the necessary pressure for spraying. Valves may also be provided in the lines to control the connection and disconnection of the lines and to regulate the flow of the solution containing the catalytically active component.

As shown in fig. 1, the porous carrier supply unit is used to supply the porous carrier to the drum body 301. The porous carrier supply unit comprises a porous carrier storage tank 101, and the position of a porous carrier outlet of the porous carrier storage tank 101 corresponds to the position of a feed port 308 of the rotary drum body 301, so that the porous carrier is fed into the rotary drum body 301 through the feed port 308.

The drum body 301 and the structure thereof have been described in detail above, and will not be described in detail here.

As shown in fig. 1, a spray bar 303 is disposed in the drum body 301, and at least one atomizing nozzle for spraying a solution containing a catalytically active component on the surface of the porous carrier is disposed on the spray bar 303.

The impregnation unit further comprises a base 302 for supporting the drum body 301, the drum body 301 being rotatably connected to the base 302.

The axis of the drum body 301 is disposed horizontally with respect to the horizontal plane, and the detailed manner of disposing the drum body 301 is described in detail above and will not be described in detail here.

Preferably, as shown in fig. 1, the dipping unit further comprises a driving device for driving the drum body 301 to rotate. As shown in fig. 1, the driving device generally includes a power generation part 306 and a transmission part 307, and the transmission part 307 is used for transmitting the power output by the power generation part 306 to the drum body 301 and causing it to rotate. The power generating component 306 may be any of various components capable of generating and outputting power, such as a motor. The transmission member 307 may be a combination of one or more of various power transmission members such as a transmission gear, a worm gear, a transmission belt, and a screw. The rotation speed of the drum body 301 can be adjusted according to the desired impregnation effect. Typically, the driving device is such that the rotating speed of the drum body 301 is 2 to 15 revolutions per minute, preferably 2 to 10 revolutions per minute, more preferably 3.5 to 4.5 revolutions per minute.

The drying unit is used for drying the impregnated porous carrier from the impregnation unit. As shown in fig. 1, the drying unit may include a drying belt 401 and a distributor 402.

A distributor 402 is used to receive the impregnated porous support output from the impregnation unit and transfer it to the carrying surface of the drying belt 401. The distributor 402 may be any of various components capable of performing the above-described functions. In a preferred embodiment, as shown in fig. 1, the distributor 402 comprises a cylinder and at least one openable inlet and at least one openable outlet provided on the cylinder. The inlet of the distributor 402 is positioned in correspondence with the position of the at least one port of the drum body to receive the impregnated porous support from the impregnation unit, and the outlet of the distributor 402 is positioned sufficiently to transfer the impregnated porous support to the drying belt 401.

The drying belt 401 serves to receive the impregnated porous support that is output from the drum body 301 and to dry the impregnated porous support on the carrying surface of the drying belt 401. The material of the drying belt 401 is such that it can withstand the temperature required for drying. Generally, the material of the drying belt 401 is sufficient to withstand a temperature of 50 to 300 ℃, preferably 60 to 250 ℃.

The drying belt 401 may be disposed in a housing 403 as needed, and a vacuum line is provided in the housing 403, so that drying can be performed under reduced pressure.

According to specific needs, the impregnation system may further include a roasting device to roast the dried porous support. The roasting device may be a device that can perform a roasting function, and is not particularly limited, such as a roasting furnace.

When the method according to the present invention is carried out using the above-described production system, the following procedure can be employed.

The porous carrier is charged into the porous carrier reservoir 101, and the solution containing the catalytically active component is placed in the solution reservoir 201 containing the catalytically active component. The feed inlet 308 on the drum body 301 is directed toward the porous carrier outlet of the porous carrier reservoir 101 to feed the porous carrier into the porous carrier reservoir 101. The power generation part 306 is turned on to drive the drum body 301 to rotate through the rotation shaft 305.

And (3) opening valves on pipelines connecting the solution storage tank 201 containing the catalytic active components and the spray rod 303, and communicating the solution storage tank 201 containing the catalytic active components with the spray rod 303, so that the solution containing the catalytic active components is sprayed on the surface of the porous carrier through an atomizing nozzle on the spray rod 303 and is adsorbed by the porous carrier.

After the impregnation is completed, the rotation of the drum body 301 is stopped, and the discharge port 309 of the drum body 301 is directed to the inlet of the distributor 402 to transfer the impregnated porous carrier to the drying belt 401 for drying.

After drying, the dried porous carrier is optionally sent to a roasting device for roasting.

According to a second aspect of the invention, there is also provided a shell distributed catalyst prepared by the process of the invention.

The shell-distributed catalyst prepared by the method has higher shell rate and high strength and forming rate.

The "shell-distributed catalyst" is also commonly referred to as an egg-shell heterogeneous catalyst, which is abbreviated as an egg-shell catalyst, and is well known to those skilled in the art, for example, as defined in (the book "catalyst support preparation and application technology" by the Zhuhong method, 199 pages (1 st edition, 2002) in the present invention, the shell rate is measured by a Scanning Electron Microscope-Energy Spectrometry (SEM-EDX) method, in the present invention, the shell rate is measured by a method comprising randomly selecting 30 catalyst particles and cutting the catalyst particles in the radial direction, observing the cross-sectional particle size of the catalyst particles by SEM, and then Scanning the catalyst particles in the radial direction by EDX to obtain the radial distribution of the catalytically active component, and the recording rate of each point in the radial direction of the support in the result of characterization by Scanning Electron Microscope-X ray Energy Spectrometry (SEM-EDX) corresponds to the element content of the point, although the magnitude of the count rate may not represent the actual content of the point element, the magnitude of the count rate can reflect the content of the point element. Therefore, in order to express the distribution rule of the catalytically active component and the co-agent in the radial direction of the carrier, a distribution factor σ is introduced, which is the ratio of the concentration of the catalytically active component and the co-agent at the center of the catalyst to the concentration at a position other than the center. Generally, the "eggshell catalyst" refers to: the catalyst has a distribution factor sigma of 0-0.95, wherein the concentration at a certain position is the average value of 20 numerical point counting rates near a certain point (the position deviation is less than or equal to 20nm) except the central point; the concentration at the center is the average value of 20 numerical point counting rates near the center point (the position deviation is less than or equal to 20 nm). The shell-distributed catalyst of the invention means that active metal components in the catalyst are mainly distributed on the shell. The percentage of the 30 catalyst particles tested that were shell distributed catalyst particles was referred to as the shell fraction.

The catalyst according to the invention is particularly suitable as a catalyst for reactions controlled by internal diffusion, such as the Fischer-Tropsch synthesis reaction.

Thus, according to a third aspect of the present invention, there is also provided a fischer-tropsch synthesis process comprising contacting synthesis gas with a catalyst under fischer-tropsch synthesis reaction conditions, wherein the catalyst is a shell distributed catalyst having a catalytic effect on fischer-tropsch synthesis reactions prepared by the process of the present invention.

According to the catalyst provided by the invention, before use, the active metal component in an oxidation state is subjected to reduction activation, preferably in the presence of hydrogen. The conditions for reductive activation may include: the reduction temperature may be 200 ℃ to 1000 ℃, preferably 200 ℃ to 800 ℃, the reduction time may be 1 to 96 hours, preferably 2 to 24 hours, the reduction activation may be carried out in pure hydrogen, or in a mixed gas of hydrogen and an inert gas, such as a mixed gas of hydrogen and nitrogen, and the hydrogen pressure may be 0.1 to 4MPa, preferably 0.1 to 2MPa, the inert gas refers to a gas that does not participate in the chemical reaction under the conditions of the present invention, such as nitrogen and a group zero element gas.

According to the Fischer-Tropsch synthesis method of the present invention, the specific reaction conditions for the Fischer-Tropsch reaction are not particularly limited, and the reaction can be carried out under conventional conditions. Specifically, the temperature can be 170-350 ℃, preferably 180-300 ℃; the total pressure can be 1-20MPa, preferably 1.5-15 MPa; the gas hourly space velocity of the synthesis gas can be 1000-^-1Preferably 2000-^-1。

The present invention will be described in detail with reference to examples, but the present invention is not limited thereto.

In the following examples and comparative examples, the composition of the prepared catalyst was measured by X-ray fluorescence spectroscopy.

In the following examples and comparative examples, the distribution of the catalytically active component in the radial direction of the porous carrier was determined by the Scanning Electron Microscope-Energy Dispersive Spectrometry (i.e., SEM-EDX), and the shell ratio was calculated.

In the following examples and comparative examples, the size of atomized droplets was measured as the volume average particle diameter using a malvern particle size analyzer.

In the following embodiments, the drum body 301 is ellipsoidal.

Example 1

1. As shown in fig. 1, 200kg of butterfly-shaped γ -alumina particles (particle length 2 to 8mm, water absorption measured as 0.8 ml/g) extruded from a 1.6mm orifice plate were used as a catalyst carrier and placed in a porous carrier tank 101.

2. Cobalt nitrate was dissolved in water to prepare an impregnation solution (concentration of cobalt nitrate was 330 g/l in terms of CoO) and placed in a solution tank 201 containing a catalytically active component.

3. Will be porousThe carrier is fed into a rotary drum body 301, the rotary drum body 301 (the axial length of the rotary drum body 301 is 3.5 meters, the maximum radial inner diameter (diameter) is 1 meter, and the minimum radial inner diameter (diameter) is 0.3 meter), a lifting plate 304 is arranged on the inner wall of the rotary drum body 301, the axial section of the lifting plate 304 is in a circular arc shape, x is 2.2y, and z is 0.2R, the rotary drum body 301 is horizontally arranged, wherein x is the chord length of the bottom arc of the radial section of the lifting plate, y is the height of the radial section of the lifting plate, z is the distance between two adjacent rows of flaky protrusions, and R is the radial maximum inner radius of the rotary drum body), the rotation speed is 3.5 revolutions per minute, impregnation liquid is fed into the rotary drum body 301, and the impregnation liquid is sprayed on the surface of the porous carrier in the form of atomized liquid drops through an atomization. Wherein the spraying amount V of the impregnating solution_LTotal pore volume V with porous support_CSatisfies the ratio of_L/V_C0.5, the size of the atomized droplets is 80 μm; the temperature in the drum body 301 was 25 ℃, and the residence time of the porous carrier in the drum body 301 was 30 minutes.

4. After the completion of the impregnation, the impregnated sample was entirely transferred to the drying belt 401 for drying within 5 minutes, wherein the drying was performed under normal pressure at a temperature of 160 ℃ and the retention time of the impregnated sample on the drying belt 401 was 4 hours.

5. The dried sample was calcined at a temperature of 400 ℃ for 4 hours, to thereby obtain a catalyst. The composition of the catalyst and the shell fraction are shown in table 1, the radial cross section of the porous support from the outer layer to the core, and the relative percentage of cobalt element is shown in table 2. The particle size distribution is listed in table 3.

Comparative example 1

A catalyst was prepared in the same manner as in example 1, except that the axial length of the drum body 301 was 3.5 m, the maximum radial inner diameter (diameter) was 2m, and the minimum radial inner diameter (diameter) was 0.6 m. The composition of the prepared catalyst and the shell fraction are shown in table 1, and the relative percentage of cobalt element is shown in table 2, from the outer layer to the core in the radial section of the porous support. The particle size distribution is listed in table 3.

Comparative example 2

A catalyst was prepared in the same manner as in example 1, except that the axial length of the drum body 301 was 1.3 m, the maximum radial inner diameter (diameter) was 2.8 m, and the minimum radial inner diameter (diameter) was 0.6 m. The composition of the prepared catalyst and the shell fraction are shown in table 1, and the relative percentage of cobalt element is shown in table 2, from the outer layer to the core in the radial section of the porous support. The particle size distribution is listed in table 3.

Comparative example 3

The catalyst was prepared according to CN204911534U, the method disclosed in example 1, except that in step 3, the vacuum pump was not turned on during spraying, i.e. no vacuum was drawn during spraying.

The composition of the prepared catalyst and the shell fraction are shown in table 1, and the relative percentage of cobalt element is shown in table 2, from the outer layer to the core in the radial section of the porous support. The particle size distribution is listed in table 3.

Comparative example 4

The catalyst was prepared according to CN204503105U, the method disclosed in example 1, except that in step 3, the vacuum pump was not turned on during spraying, i.e. no vacuum was drawn during spraying.

Example 2

1. 300kg of butterfly-shaped γ -alumina particles (particle length 2 to 8mm, water absorption measured 1.0 ml/g) extruded from a 1.6mm orifice plate were used as a catalyst carrier and placed in the porous carrier tank 101.

2. Dissolving ammonium metatungstate and nickel nitrate in water to prepare impregnation liquid (WO)₃Was 402 g/l and the concentration of NiO was 25 g/l) and placed in the solution reservoir 201 containing the catalytically active component.

3. The porous carrier is sent into a drum body 301, the drum body 301 is rotated (the axial length of the drum body 301 is 4 meters, the maximum radial inner diameter (diameter) is 1 meter, the minimum radial inner diameter (diameter) is 0.3), and the drum body is rotatedThe inner wall of the body 301 is provided with a material raising plate 304, the axial section of the material raising plate 304 is arc-shaped, x is 2y, z is 0.2R, the rotary drum body 301 is horizontally arranged, wherein x is the chord length of the bottom arc of the radial section of the material raising plate, y is the height of the radial section of the material raising plate, z is the distance between two adjacent rows of flaky protrusions, R is the radial maximum inner radius of the rotary drum body), the rotating speed is 4.5R/min, the impregnation liquid is fed into the rotary drum body 301, and the impregnation liquid is sprayed on the surface of the porous carrier in the form of atomized liquid drops through an atomizing nozzle. Wherein the spraying amount V of the impregnating solution_LTotal pore volume V with porous support_CSatisfies the ratio of_L/V_C0.4, the size of the atomized droplets is 100 μm; the temperature in the drum body 301 was 50 ℃, and the residence time of the porous carrier in the drum body 301 was 24 minutes.

4. After completion of the impregnation, the whole of the impregnated sample was sent to a drying belt 401 for drying within 6 minutes, wherein the drying was carried out under normal pressure at a temperature of 120 ℃ under reduced pressure at a pressure (gauge pressure) of-8 kPa, and the retention time of the impregnated sample on the drying belt 401 was 2 hours.

5. The dried sample was calcined at a temperature of 450 ℃ for 2 hours, to thereby obtain a catalyst. The composition of the catalyst and the shell fraction are given in table 1, the radial section of the porous support from the outer layer to the core, and the relative percentage of tungsten element is given in table 2. The particle size distribution is listed in table 3.

Example 3

1. 500kg of butterfly-shaped γ -alumina particles (particle length 2 to 8mm, water absorption measured 1.0 ml/g) extruded from a 1.6mm orifice plate were used as a catalyst carrier and placed in the porous carrier tank 101.

2. Dissolving ammonium molybdate, ammonium metatungstate, nickel nitrate and phosphoric acid in water to prepare impregnation liquid (MoO)₃In a concentration of 225 g/l, WO₃Has a concentration of 100 g/l, a NiO concentration of 50 g/l, P₂O₅At a concentration of 50 g/l) and placed in the impregnation fluid tank 201.

3. The porous carrier is fed into the drum body 301, and the drum body 301 (drum body) is rotatedThe axial length of the body 301 is 5 meters, the maximum radial inner diameter (diameter) is 1 meter, the minimum radial inner diameter (diameter) is 0.3 meter, the inner wall of the rotary drum body 301 is provided with a material raising plate 304, the axial section of the material raising plate 304 is arc-shaped, x is 2y, z is 0.2R, the rotary drum body 301 is horizontally arranged, wherein x is the chord length of the bottom arc of the radial section of the material raising plate, y is the height of the radial section of the material raising plate, z is the distance between two adjacent rows of flaky protrusions, and R is the radial maximum inner radius of the rotary drum body), the rotating speed is 3.5 revolutions per minute, the impregnation liquid is sent into the rotary drum body 301, and the impregnation liquid is sprayed on the surface of the porous carrier in the form of atomized liquid drops through an atomization nozzle. Wherein the spraying amount V of the impregnating solution_LTotal pore volume V with porous support_CSatisfies the ratio of_L/V_C0.31, the size of the atomized droplets is 100 μm; the temperature in the drum body 301 was 50 ℃, and the residence time of the porous carrier in the drum body 301 was 24 minutes.

5. The dried sample was calcined at a temperature of 400 ℃ for 2 hours, to thereby obtain a catalyst. The composition of the catalyst and the shell fraction are shown in table 1, the radial section of the porous support from the outer layer to the core, and the relative percentage of molybdenum element is shown in table 2. The particle size distribution is listed in table 3.

Example 4

A catalyst was prepared in the same manner as in example 1, except that the axial length of the drum body 301 was 6 m. The composition of the resulting catalyst and the shell fraction are shown in table 1, and the relative percentage of cobalt element is shown in table 2, along the radial section of the porous support from the outer layer to the core. The particle size distribution is listed in table 3.

Example 5

A catalyst was prepared in the same manner as in example 1, except that the rotation speed of the drum body 301 was 9 revolutions per minute. The composition of the resulting catalyst and the shell fraction are shown in table 1, and the relative percentage of cobalt element is shown in table 2, along the radial section of the porous support from the outer layer to the core. The particle size distribution is listed in table 3.

Comparative example 5

The catalyst was prepared according to CN204911534U, the method disclosed in example 1, except that the axial length and the radial inner diameter of the drum body 301 were the same as those of the drum body 301 described in example 1 of the present invention, i.e., the axial length was 3.5 m and the radial inner diameter (diameter) was 1 m; in the spraying process of the step 3, the vacuum pump is not started, that is, the vacuum pumping is not performed in the spraying process, and the rotating speed of the rotating drum body 301 is 9 revolutions per minute.

Comparative example 6

The catalyst was prepared according to CN204503105U, the method disclosed in example 1, except that in step 3, the vacuum pump was not turned on during the spraying process, i.e. no vacuum was applied during the spraying process, and the rotation speed of the drum body 301 was 9 rpm.

TABLE 1

TABLE 2

*: and scanning the radial section of the catalyst from the outermost layer to the core by using EDX (enhanced-dispersive X) along the radial section, and respectively measuring the concentration of the catalytic active component at each point by taking 5 points at equal intervals to obtain the ratio of the concentration of each catalytic active component to the concentration of the aluminum element at the point.

TABLE 3

Note: in the table, 2-3mm does not include 3 nm.

As can be seen from the results of tables 1 and 2, the catalyst prepared by the method of the present invention has a high shell ratio, thereby enabling the repeated stable preparation of a shell-distributed catalyst.

As can be seen from the results in table 3, the catalyst prepared by the method of the present invention has higher strength and yield, less broken particles, less particles with a particle size of less than 2mm compared to the catalyst prepared by the prior art, and the impregnation system provided by the prior art produces more particles with a smaller particle size, and the catalyst has lower strength and yield.

As can be seen from the results of comparison between the examples and the comparative examples, the catalyst prepared by the method of the present invention has a high shell fraction, and the catalyst has high strength and yield. Further, comparing example 1 with comparative example 1, comparative example 2 and example 4, it can be seen that the preferred ratio of the axial length to the radial maximum length of the drum body of the present invention is more favorable for optimizing the catalyst properties; comparing example 1 with comparative example 3, it can be seen that the preferred shape of the drum body of the present invention matches the horizontal arrangement of the drum body, which is more beneficial to optimizing the catalyst properties; comparing example 5 with comparative example 5, it can be seen that the catalyst prepared by the method provided by the invention is less broken and has higher shell rate under larger rotating speed than the method provided by the prior art even though the axial length and the radial inner diameter are the same. Comparing example 5 with comparative example 6, it can be seen that the catalyst prepared by the method provided by the invention is less broken and has higher shell rate at a higher rotating speed than the method provided by the prior art. It should be noted that, in the method provided by the invention, the drum body is horizontally arranged, namely, the shell-type catalyst is prepared intermittently, which is more favorable for monitoring the product quality, and when a batch of materials has problems, the problem can be remedied in time, so that the method is simpler and easier to control.

Test example 1

The catalysts prepared by the above examples and comparative examples were tested for performance by the following method.

The test procedure was carried out in a fixed bed fischer-tropsch synthesis reactor using 5 g of catalyst.

The catalyst is reduced prior to use. The reduction is carried out at atmospheric pressure, with the other conditions being: the hydrogen flow was 1000NL/(g-cat h), and the temperature was raised to 400 ℃ at a rate of 4 ℃/min and held for 5 h.

The Fischer-Tropsch synthesis reaction temperature is 220 ℃, and H₂The ratio of/CO is 2, the pressure is 2.5MPa, and the Gas Hourly Space Velocity (GHSV) is 2000h^-1. The results are listed in table 4.

TABLE 4

In Table 4, X_COThe conversion rate of CO is shown in the specification,

and

respectively represent C₅Above (containing C)₅) Selectivity for hydrocarbons and CH₄Selectivity of (2). The specific definition is shown in the following expression:

wherein, V₁And V₂Respectively representing the volume of feed gas entering the reaction system and the volume of tail gas flowing out of the reaction system in a certain time period under a standard condition; c. C₁And c₂Respectively representing the content of corresponding substances in the feed gas and the tail gas. n is_conThe mole number of CO participating in the reaction through the reaction bed layer in a certain period of time,

to convert into CO₂The number of moles of CO of (a),

to convert into CH₄The number of moles of CO of (a),

to convert into CH₄、C₂Hydrocarbons, C₃Hydrocarbons, and C₄Moles of CO of the hydrocarbon.

As can be seen from the results in Table 4, catalyst pair C produced by the process of the present invention₅₊Hydrocarbons have higher selectivity, lower selectivity to methane, and higher CO conversion.

The preferred embodiments of the present invention have been described above in detail, but the present invention is not limited thereto. Within the scope of the technical idea of the invention, many simple modifications can be made to the technical solution of the invention, including combinations of various technical features in any other suitable way, and these simple modifications and combinations should also be regarded as the disclosure of the invention, and all fall within the scope of the invention.

Claims

1. A method of preparing a shell-distributed catalyst, the method comprising:

placing a porous carrier in a hollow rotary drum body, spraying a solution containing a catalytic active component on the surface of the porous carrier, wherein the total spraying amount of the solution is less than the total pore volume of the porous carrier, the rotary drum body is provided with an openable feed inlet for receiving the porous carrier and an openable discharge outlet for outputting the porous carrier, the rotary drum body is in an ellipsoidal shape, the ratio of the axial length to the radial maximum length of the rotary drum body is 3-9, the rotary drum body is horizontally arranged, the porous carrier loaded with the solution leaves the rotary drum body through the discharge outlet, then supplementing the porous carrier into the rotary drum body through the feed inlet, and drying and optionally roasting the porous carrier leaving the container.

2. The method of claim 1, wherein the ratio of the axial length to the radial maximum length of the drum body is 3-5.

3. The method according to claim 1, wherein the solution is sprayed onto the surface of the porous support in the form of atomized droplets, the spraying conditions being such that the atomized droplets formed have an average diameter in the range of 1-600 microns.

4. A method according to claim 3, wherein the spraying conditions are such that the mean diameter of the atomized droplets formed is in the range 20-400 microns.

5. A method according to claim 4, wherein the spraying conditions are such that the mean diameter of the atomized droplets formed is in the range 50-300 microns.

6. The method of claim 1, wherein the total sprayed amount of solution is V_LThe total pore volume of the porous carrier is V_C，V_L/V_C=0.01-0.99。

7. The method of claim 6, wherein V_L/V_C=0.1-0.8。

8. The method of any one of claims 1-7, wherein the drum body is rotated about an axis during spraying.

9. The method of claim 8, wherein the rotating drum body rotates at a speed of 2-15 rpm.

10. The method of claim 9, wherein the rotating drum body rotates at a speed of 3.5-4.5 rpm.

11. The method as claimed in any one of claims 1 to 7, wherein a lifter plate is provided on an inner wall surface of the drum body.

12. The method of claim 11 wherein the material raising plate is a sheet-like projection.

13. The method as claimed in claim 12, wherein the edges of the sheet-like projections facing the cavity of the drum body are smoothly curved.

14. The method according to any one of claims 1 to 7, wherein the drying is carried out at a temperature of 50-290 ℃; the calcination is carried out at a temperature of 300-600 ℃.

15. The method of claim 14, wherein the drying is performed at a temperature of 60-250 ℃.

16. The method of any one of claims 1-7,

the porous carrier is one or more than two of silicon oxide, aluminum oxide, silicon oxide-aluminum oxide, aluminum silicate, titanium oxide, zirconium oxide and active carbon;

the catalytically active component is selected from the group VIII metal elements.

17. The method of claim 16, wherein the group VIII metal element is at least one of iron, cobalt, and ruthenium.

18. The process according to any one of claims 1 to 7, wherein the loading of the catalytically active component on the porous support is such that the content of the catalytically active component, calculated as oxide, is from 0.5 to 60% by weight, based on the total amount of the finally prepared catalyst.

19. The method according to claim 18, wherein the content of the catalytically active component is 1 to 50 wt.%, calculated as oxide.

20. A shell distributed catalyst prepared by the method of any one of claims 1-19.

21. A fischer-tropsch synthesis process comprising contacting synthesis gas with a catalyst under fischer-tropsch synthesis reaction conditions, wherein the catalyst is a shell distributed catalyst prepared by a process as claimed in any one of claims 16 to 19.