CN116060045A - Catalyst for preparing olefin by dehydrogenating low-carbon alkane and preparation method and application thereof - Google Patents

Catalyst for preparing olefin by dehydrogenating low-carbon alkane and preparation method and application thereof Download PDF

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CN116060045A
CN116060045A CN202111290648.3A CN202111290648A CN116060045A CN 116060045 A CN116060045 A CN 116060045A CN 202111290648 A CN202111290648 A CN 202111290648A CN 116060045 A CN116060045 A CN 116060045A
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catalyst
impregnation
metal
group
metal compound
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纪中海
刘昌呈
王春明
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Sinopec Research Institute of Petroleum Processing
China Petroleum and Chemical Corp
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Sinopec Research Institute of Petroleum Processing
China Petroleum and Chemical Corp
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J27/00—Catalysts comprising the elements or compounds of halogens, sulfur, selenium, tellurium, phosphorus or nitrogen; Catalysts comprising carbon compounds
    • B01J27/06—Halogens; Compounds thereof
    • B01J27/135—Halogens; Compounds thereof with titanium, zirconium, hafnium, germanium, tin or lead
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C5/00—Preparation of hydrocarbons from hydrocarbons containing the same number of carbon atoms
    • C07C5/32—Preparation of hydrocarbons from hydrocarbons containing the same number of carbon atoms by dehydrogenation with formation of free hydrogen
    • C07C5/327—Formation of non-aromatic carbon-to-carbon double bonds only
    • C07C5/333—Catalytic processes
    • C07C5/3335—Catalytic processes with metals
    • C07C5/3337—Catalytic processes with metals of the platinum group
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P20/00—Technologies relating to chemical industry
    • Y02P20/50—Improvements relating to the production of bulk chemicals
    • Y02P20/52—Improvements relating to the production of bulk chemicals using catalysts, e.g. selective catalysts
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P20/00—Technologies relating to chemical industry
    • Y02P20/50—Improvements relating to the production of bulk chemicals
    • Y02P20/584—Recycling of catalysts

Abstract

The invention relates to a catalyst for preparing olefin by dehydrogenating low-carbon alkane, which comprises an alumina carrier, 0.1-5.0 wt% of group VIII metal, 0.1-3.0 wt% of second metal component, 0.1-3.0 wt% of group IA metal, 0.3-5.0 wt% of halogen and 0.1-5.0 wt% of boron, wherein the second metal component is selected from tin, germanium, lead, indium, gallium or thallium based on the dry weight of the alumina carrier. The catalyst provided by the invention has higher raw material conversion rate and selectivity of target products, and can effectively inhibit carbon deposition.

Description

Catalyst for preparing olefin by dehydrogenating low-carbon alkane and preparation method and application thereof
Technical Field
The invention relates to a catalyst for preparing olefin by dehydrogenating low-carbon alkane, a preparation method and application thereof.
Background
Propylene is an important basic organic chemical raw material and is widely applied to the production of various chemical products such as polypropylene, acetone, acrylonitrile, propylene oxide, acrylic acid and the like. Currently, propylene supplies are mainly from the naphtha cracking process to make ethylene and petroleum catalytic cracking by-products.Since the 90 s of the last century, the traditional propylene production process has failed to meet the propylene demand in the chemical industry, and other alternative process technologies must be accelerated. Among them, the process of producing propylene by dehydrogenation of propane is of greatest interest. The technology of propylene preparation by catalytic dehydrogenation of propane, which is already industrialized at present, mainly comprises Oleflex technology of UOP company and Catofin technology of Lummes company. The Oleflex process adopts a moving bed reactor with continuously regenerated catalyst, and adopts Pt-Sn/Al 2 O 3 K, li or the like is added as a catalyst for modification; the Catofin process adopts a fixed bed reactor, and uses Cr 2 O 3 /Al 2 O 3 The catalyst is deactivated fast and needs to be regenerated once every 15 minutes.
The propane catalytic dehydrogenation reaction is limited by thermodynamic equilibrium, and the high temperature and the low pressure are favorable for the reaction. However, too high a reaction temperature increases the propane cracking reaction, so that carbon deposition is serious and the catalyst deactivation rate is accelerated, so that the development of a propane dehydrogenation catalyst with high activity, high selectivity and high stability becomes a key of the technology.
Supported platinum-based catalysts are an important class of low-carbon alkane dehydrogenation catalysts. CN106588544 and CN106582629 disclose a dehydrogenation catalyst of propylene, the carrier is alumina, the active component is platinum group metal, the auxiliary agent includes group IIIA element, tin and carbon, the group IIIA element is gallium or boron, the mass content of the auxiliary agent is 0.001-7% based on the total mass of the catalyst; the mass content of the carrier is 97-98.4%; the mass content of the active component is 0.3-0.5%; the mass content of the IIIA group element is 0.2-1%; the mass content of the tin is 1.0-2.0%; the mass content of the carbon is 0.1-0.3%; CN106588547 discloses a propane dehydrogenation catalyst, which consists of a carrier alumina, and platinum group metal elements and boron elements supported on the carrier, wherein the content of the platinum group metal elements is 0.4-0.6 wt% and the content of the boron elements is 0.1-0.6 wt% based on the weight of the dehydrogenation catalyst.
CN108014795 discloses a propane dehydrogenation catalyst. The propane dehydrogenation catalyst is prepared by using theta-Al 2 O 3 The catalyst is a carrier, a metal component is supported on the carrier, pt and In the metal component are essential components, K and/or Ga are supported or not supported on the carrier as auxiliary agents, and Pt is theta-Al In terms of elements 2 O 3 0.005-0.2% by weight of carrier, in being calculated as element theta-Al 2 O 3 0.1-2.0% of carrier weight, K is theta-Al in terms of element 2 O 3 0-2.0% of carrier weight, ga being theta-Al in terms of element 2 O 3 0-2.0% by weight of carrier. The propane dehydrogenation catalyst prepared by the method has good propane dehydrogenation reaction performance, and compared with the traditional Pt-based propane dehydrogenation catalyst, the catalyst has the advantages that the loading amount of noble metal Pt is greatly reduced, and the production cost can be greatly reduced.
Disclosure of Invention
The invention aims to provide a catalyst for preparing olefin by dehydrogenating low-carbon alkane, a preparation method and application thereof.
In order to achieve the above object, a first aspect of the present invention provides a catalyst for preparing olefin by dehydrogenating light alkane, the catalyst comprising an alumina carrier and the following active components in content based on the dry weight of the alumina carrier:
Figure BDA0003334744920000021
Figure BDA0003334744920000031
the second metal component is selected from tin, germanium, lead, indium, gallium or thallium.
Optionally, the catalyst comprises 0.1 to 1.5 wt% of the group VIII metal, 0.1 to 1.5 wt% of the second metal component, 0.5 to 2.0 wt% of the group IA metal, 0.3 to 2.0 wt% of the halogen and 0.1 to 3.0 wt% of the boron.
Optionally, the catalyst comprises 0.1 to 0.5 wt% of the group VIII metal, 0.1 to 1.0 wt% of the second metal component, 0.5 to 1.8 wt% of the group IA metal, 0.5 to 1.8 wt% of the halogen and 0.1 to 2.0 wt% of the boron.
Optionally, the alumina support contains θ -alumina; the specific surface of the alumina carrier is 50-130m 2 Per gram, pore volume is 0.6-0.75 ml/g.
Optionally, the group viii metal is one or more of platinum, ruthenium, rhodium, palladium, iridium and osmium, preferably platinum;
the second metal component is tin;
the group IA metal is one or more of potassium, lithium, sodium, rubidium and cesium, preferably potassium;
the halogen is one or more of chlorine, bromine and fluorine, preferably chlorine.
In a second aspect, the present invention provides a process for preparing the catalyst provided in the first aspect of the invention, the process comprising:
s1, carrying out first impregnation on an alumina carrier containing a second metal component by adopting a first impregnation liquid containing hydrochloric acid and a VIII metal compound, taking out a solid subjected to first impregnation, and carrying out first roasting to obtain a first solid product;
s2, contacting the first solid product with a second impregnating solution containing a group IA metal compound to carry out second impregnation, taking out the solid after the second impregnation and carrying out second roasting to obtain a second solid product;
wherein the boron has been impregnated on the first alumina support containing a second metal component prior to contacting the first solid product with the second impregnation liquid containing a group IA metal compound for a second impregnation;
s3, sequentially carrying out oxychlorination treatment and reduction treatment on the second solid product.
Optionally, the group viii metal compound is selected from one or more of chloroplatinic acid, ammonium chloroplatinate and platinum chloride, preferably chloroplatinic acid;
the group IA metal compound is selected from one or more of hydroxide, nitrate and chloride of group IA metal, preferably one or more of potassium hydroxide, potassium nitrate and potassium chloride.
Optionally, the conditions of the first impregnation and the second impregnation each independently comprise: the temperature is 20-70 ℃ and the time is 2-6 hours;
the conditions of the oxychlorination treatment include: the temperature is 480-680 ℃ and the time is 1-10 hours, and the oxychlorination treatment is carried out in an atmosphere containing water, oxygen and chlorine-containing gas;
the conditions of the reduction treatment include: the temperature is 450-700 ℃ and the time is 0.5-20 hours.
Alternatively, the alumina support containing the second metal component is prepared by a process comprising the steps of:
forming aluminum sol containing a second metal compound by adopting an oil ammonia column or a hot oil column drop ball to obtain aluminum oxide pellets, and performing third roasting on the aluminum oxide pellets at 450-1100 ℃; or alternatively, the process may be performed,
and (3) contacting the alumina carrier with a third impregnating solution containing a second metal compound for third impregnation, taking out a solid product after the third impregnation, and performing fourth roasting at 500-630 ℃.
Optionally, the second metal compound is selected from one or more of chloride, bromide, nitrate, alkoxide and organic complex of tin;
preferably, the second metal compound is selected from one or more of stannous bromide, stannous chloride, stannic chloride pentahydrate and tetrabutyltin.
The third aspect of the invention provides a method for preparing olefin by dehydrogenating light alkane, which comprises the following steps: the dehydrogenation reaction is carried out by contacting the lower alkane with the catalyst provided in the first aspect of the present invention.
Optionally, the dehydrogenation reaction conditions include: the temperature is 400-750 ℃, the pressure is 0.1-1.0MPa, and the mass airspeed of the low-carbon alkane is 0.1-20h -1 ；
The lower alkane is selected from C 3 ～C 5 Preferably propane, pentane, n-butane or isobutane.
Through the technical scheme, the catalyst disclosed by the invention can effectively improve the carbon deposit resistance of the catalyst by adding a proper auxiliary agent and reasonably preparing the proportion of the auxiliary agent to the platinum group metal.
Additional features and advantages of the invention will be set forth in the detailed description which follows.
Detailed Description
The following describes specific embodiments of the present invention in detail. It should be understood that the detailed description and specific examples, while indicating and illustrating the invention, are not intended to limit the invention.
The invention provides a catalyst for preparing olefin by dehydrogenating low-carbon alkane, which comprises an alumina carrier and the following active components in percentage by weight based on the dry weight of the alumina carrier:
Figure BDA0003334744920000051
the second metal component is selected from tin, germanium, lead, indium, gallium or thallium.
The reaction of dehydrogenating low-carbon alkane to prepare alkene is controlled by thermodynamic, in order to make the reaction proceed to dehydrogenation direction, the reaction temperature needs to be increased and the pressure needs to be reduced, however, the high reaction temperature often causes sintering and a large amount of carbon deposition of platinum group metals with hydrogenation/dehydrogenation functions on the catalyst. The invention introduces the second metal component, the group IA metal, the halogen and the boron into the platinum group metal-containing catalyst, limits the dosage proportion of the platinum group metal, can greatly improve the stability and the selectivity of the low-carbon alkane dehydrogenation catalyst through the synergistic effect of the platinum group metal, and effectively improves the carbon deposit resistance of the catalyst.
In one embodiment of the invention, the catalyst comprises 0.1 to 1.5 wt% of the group VIII metal, 0.1 to 1.5 wt% of the second metal component, 0.5 to 2.0 wt% of the group IA metal, 0.3 to 2.0 wt% of the halogen and 0.1 to 3.0 wt% of the boron.
In one embodiment of the invention, the catalyst comprises 0.1 to 0.5 wt% of the group VIII metal, 0.1 to 1.0 wt% of the second metal component, 0.5 to 1.5 wt% of the group IA metal, 0.5 to 1.5 wt% of the halogen and 0.1 to 2.0 wt% of the boron.
In one embodiment of the invention, the alumina support contains θ -alumina; the specific surface area of the alumina carrier is 50-130m 2 Per gram, pore volume is 0.6-0.75 ml/g. Among them, the detection method of specific surface area and pore volume is well known to those skilled in the art, and can be detected by, for example, the BET method.
In one embodiment of the invention, the group VIII metal is one or more of platinum, ruthenium, rhodium, palladium, iridium and osmium, preferably platinum; the second metal component is tin; the group IA metal is one or more of potassium, lithium, sodium, rubidium and cesium, preferably potassium; the halogen is one or more of chlorine, bromine and fluorine, preferably chlorine.
In a second aspect, the present invention provides a method for preparing the catalyst provided in the first aspect, the method comprising: s1, carrying out first impregnation on an alumina carrier containing a second metal component by adopting a first impregnation liquid containing hydrochloric acid and a VIII metal compound, taking out a solid subjected to first impregnation, and carrying out first roasting to obtain a first solid product; s2, contacting the first solid product with a second impregnating solution containing a group IA metal compound to carry out second impregnation, taking out the solid after the second impregnation and carrying out second roasting to obtain a second solid product; wherein the boron has been impregnated onto the first alumina support containing the second metal component prior to contacting the first solid product with the second impregnation fluid containing the group IA metal compound for a second impregnation; s3, sequentially carrying out oxychlorination treatment and reduction treatment on the second solid product.
According to the present invention, the phrase "the boron has been impregnated to be supported on the first alumina support containing the second metal component" before the first solid product is brought into contact with the second impregnation liquid containing the group IA metal compound for the second impregnation "means that: the boron may be impregnated prior to impregnating the group viii metal to the support such that the boron is supported on the support; it is also possible to impregnate the boron after impregnating the group VIII metal on the support, so that the boron is supported on the support; boron may also be co-impregnated with the group VIII metal and supported on the support.
In one embodiment of the present invention, the first impregnation liquid is used in an amount of 0.5 to 2.0 wt% of a group IA metal compound based on the group IA metal, based on the dry weight of the alumina carrier; the second impregnation fluid is used in an amount of 1.0 to 3.0L relative to 1kg of the alumina carrier containing the second metal component.
In one embodiment of the present invention, the solids to be calcined may be first dried prior to the calcination step of steps S1 and S2, drying conditions well known to those skilled in the art may include: the temperature is 100-300 ℃ and the time is 1-48 hours.
In one embodiment of the present invention, step S1 includes: and (3) carrying out first impregnation on the alumina carrier containing the second metal component by adopting a first impregnation liquid containing hydrochloric acid, a group VIII metal compound and a boron compound, taking out the solid subjected to the first impregnation, and carrying out first roasting on the solid to obtain a first solid product. Wherein, in a specific embodiment of the invention, the content of the hydrochloric acid in the first impregnating solution is 0.2 to 2.0 weight percent based on the dry weight of the alumina carrier, the content of the group VIII metal compound is 0.1 to 0.5 weight percent based on the group VIII metal, and the content of the boron-containing compound is 0.1 to 3.0 weight percent; the first impregnation fluid is used in an amount of 1.0 to 3.0L relative to 1kg of the alumina carrier containing the second metal component.
In another embodiment of the present invention, step S1 includes: and (3) carrying out fourth impregnation on the alumina carrier containing the second metal component by adopting a fourth impregnation liquid containing a boron compound, taking out the solid subjected to fourth impregnation, carrying out fifth roasting, and enabling the solid product subjected to fifth roasting to be in contact with the first impregnation liquid for first impregnation, so as to obtain a first solid product. Wherein, in a specific embodiment of the invention, the content of the hydrochloric acid in the first impregnating solution is 0.2 to 2.0 weight percent based on the dry weight of the alumina carrier, the content of the group VIII metal compound is 0.1 to 0.5 weight percent based on the group VIII metal, and the content of the boric acid is 0.1 to 3.0 weight percent; the fourth impregnating solution contains 0.1-3.0% by weight of boron-containing compound, 1.0-3.0L of the first impregnating solution and 1.0-3.0L of the fourth impregnating solution relative to 1kg of the alumina carrier containing the second metal component.
In another embodiment of the present invention, step S1 includes: and (3) carrying out first impregnation on the alumina carrier containing the second metal component by adopting a first impregnation liquid containing hydrochloric acid and a group VIII metal compound, taking out the solid after the first impregnation and carrying out first roasting, contacting the product after the first roasting with a fifth impregnation liquid containing a boron compound to carry out fifth impregnation, and taking out the solid after the fifth impregnation and carrying out sixth roasting to obtain a first solid product. The content of the hydrochloric acid in the first impregnating solution is 0.2 to 2.0 weight percent based on the dry weight of the alumina carrier, the content of the group VIII metal compound is 0.1 to 0.5 weight percent based on the group VIII metal, and the content of the boron-containing compound in the fifth impregnating solution is 0.1 to 3.0 weight percent; the first impregnating solution is used in an amount of 1.0 to 3.0L and the fifth impregnating solution is used in an amount of 1.0 to 3.0L relative to 1kg of the alumina carrier containing the second metal component. In the present invention, the conditions of the first firing may include: the temperature is 500-700 ℃ and the time is 1-10 hours.
In one embodiment of the present invention, the group viii metal compound is selected from one or more of chloroplatinic acid, ammonium chloroplatinate and platinum chloride, preferably chloroplatinic acid; the group IA metal compound is selected from one or more of hydroxide, nitrate and chloride of group IA metal, preferably one or more of potassium hydroxide, potassium nitrate and potassium chloride.
In one embodiment of the present invention, the conditions for the second firing include: the temperature is 500-700 ℃ and the time is 1-10 hours.
In one embodiment of the invention, the conditions of the first impregnation and the second impregnation each independently comprise: the temperature is 20-70deg.C, preferably 20-40deg.C, for 2-6 hr, and for 2-5 hr.
The oxychlorination and reduction treatments of the catalyst according to the invention are well known to those skilled in the art, and in one embodiment of the invention the conditions of the oxychlorination treatment comprise: the temperature is 480-680 ℃ and the time is 1-10 hours, and the oxychlorination treatment is carried out in an atmosphere containing water, oxygen and chlorine-containing gas; the conditions of the reduction treatment include: the temperature is 450-700 ℃, preferably 500-650 ℃, and the time is 0.5-20 hours, preferably 2-10 hours. The reduction treatment is performed in a reducing atmosphere, and the reducing atmosphere may contain a reducing gas such as hydrogen, or a mixture of hydrogen and an inert gas. The catalyst is subjected to oxychlorination and reduction under the above conditions, so that the group VIII metal is fully dispersed in the carrier and reduced to the corresponding metal state.
According to the invention, the second metal component of the alumina carrier containing the second metal component is introduced at the time of shaping the carrier. In one embodiment of the invention, the alumina sol containing the second metal compound is formed by adopting an oil ammonia column or a hot oil column to obtain alumina pellets, and the alumina pellets are subjected to third roasting at 450-1100 ℃. Wherein the drop ball formation of the oil ammonia column or the hot oil column is a method well known to those skilled in the art. In one embodiment, the method for preparing the aluminum sol used for the dropping balls comprises the steps of reacting aluminum trichloride and ammonia water at 50-90 ℃, preferably 50-80 ℃, filtering, washing with water, and adding an acid solution into a filter cake to form the aluminum sol; or directly adding water into aluminum hydroxide powder to prepare slurry, and then adding acid into the slurry to prepare aluminum sol. The acid used is preferably nitric acid or hydrochloric acid, to which organic acids, such as acetic acid or citric acid, may also be added. If alumina containing macropores is prepared, a proper amount of urea, kerosene and fatty alcohol polyoxyethylene ether are added into the alumina solAnd (5) reaming agents. Drying wet ball obtained by drop ball molding, and roasting at 450-650deg.C to obtain gamma-Al 2 O 3 Roasting at 900-1100 deg.c for 1-20 hr to obtain small theta-alumina ball. Preferably, the gamma-Al 2 O 3 Treating with air containing water 2-10 vol.% at 450-650deg.C for 2-8 hr, and calcining at 900-1100 deg.C for 2-8 hr.
According to the invention, the second metal component of the alumina support containing the second metal component is introduced by impregnation after the support has been shaped. In one embodiment of the present invention, the alumina support is contacted with a third impregnation liquid containing a second metal compound to carry out a third impregnation, and the solid product after the third impregnation is taken out and subjected to a fourth calcination at 500 to 630 ℃.
In one embodiment of the present invention, the second metal compound is selected from one or more of chloride, bromide, nitrate, alkoxide and organic complex of tin; preferably, the second metal compound is selected from one or more of stannous bromide, stannous chloride, stannic chloride pentahydrate and tetrabutyltin.
The third aspect of the invention provides a method for preparing olefin by dehydrogenating light alkane, which comprises the following steps: the dehydrogenation reaction is carried out by contacting the lower alkane with the catalyst provided in the first aspect of the present invention.
In one embodiment of the present invention, the dehydrogenation reaction conditions include: the temperature is 400-750deg.C, the pressure (absolute) is 0.1-1.0MPa, preferably 550-650deg.C, and the pressure is 0.1-0.5MPa; the mass airspeed of the low-carbon alkane is 0.1 to 20h -1 Preferably 0.5 to 10 hours -1 . The lower alkane is selected from C 3 ～C 5 Preferably propane, pentane, n-butane or isobutane.
In one embodiment of the present invention, the dehydrogenation reaction may also be carried out by mixing water vapor, argon, methane, ethane, nitrogen, etc. as a diluent gas with the lower alkane, preferably the diluent gas is hydrogen. When hydrogen is selected, the molar ratio of hydrogen to lower alkane is preferably (0.1-10): 1. more preferably (0.3-3): 1.
the invention is further illustrated by the following examples, which are not intended to be limiting in any way.
The starting materials used in the following examples and comparative examples were all commercially available as not specifically described, wherein the alumina carrier 1 was produced by Sasol Corp. Germany and had a specific surface area of 125m 2 Per gram, pore volume is 0.65 ml/g. Alumina support 2 is produced by Sasol Corp. Germany and has a specific surface area of 140m 2 Per gram, pore volume is 0.8 ml/g.
The catalyst compositions in the following examples and comparative examples were measured by the ICP-OES method.
The Sn-containing theta alumina support a employed in examples 1-5 was prepared by impregnation: the alumina carrier 1 was impregnated by contact with an impregnating solution containing stannous chloride, and the impregnated solid was taken out and calcined at 650 ℃ for 5 hours to obtain a θ -alumina carrier containing Sn, wherein the content of Sn was 0.35 wt% based on the dry weight of the alumina carrier.
The preparation method of the Sn-containing theta alumina carrier b employed in example 6 was similar to that of the Sn-containing theta alumina carrier a, except that the carrier employed was alumina carrier 2.
Example 1
S1, taking a spherical Sn-containing theta-alumina carrier a, and soaking the spherical Sn-containing theta-alumina carrier a in a soaking solution containing chloroplatinic acid, hydrochloric acid and boric acid at 40 ℃ for 2 hours, wherein the soaking solution contains 0.35 weight percent of platinum, 1.0 weight percent of chlorine and 0.4 weight percent of boron (the same applies to a dry-based alumina carrier), and the liquid/solid ratio is 2.0mL/g. After impregnation, the solid was dried at 100℃for 12 hours and then calcined at 550℃for 4 hours to give a first solid product.
S2, soaking the first solid product with potassium hydroxide solution at 40 ℃ for 2 hours, wherein the content of potassium in the solution is 1.3 weight percent (relative to the alumina carrier), and the liquid/solid ratio is 2.0mL/g. The impregnated solid was dried at 100℃for 12 hours and then calcined at 600℃for 2 hours to give a second solid product.
S3, carrying out oxychlorination treatment on the second solid product for 10 hours at 550 ℃ in an atmosphere containing water, oxygen and carbon tetrachloride, and then carrying out reduction treatment at 550 ℃ for 1 hour to obtain the catalyst A, wherein the platinum content in the catalyst is 0.35 wt%, the tin content is 0.35 wt%, the potassium content is 1.3 wt%, the chlorine content is 1.0 wt% and the boron content is 0.4 wt%.
Example 2
Catalyst B was prepared in the same manner as in example 1, except that Pt was impregnated before B was impregnated in this example, and the chlorine and potassium content was increased, specifically:
taking spherical Sn-containing theta-alumina carrier, impregnating the spherical Sn-containing theta-alumina carrier for 2 hours at 40 ℃ by using impregnating solution containing chloroplatinic acid and hydrochloric acid, wherein the impregnating solution contains 0.35 weight percent of platinum and 1.3 weight percent of chlorine (relative to the dry alumina carrier), the liquid/solid ratio is 2.0mL/g, drying the solid at 100 ℃ for 12 hours after impregnation, roasting the solid at 550 ℃ for 4 hours, impregnating the solid product obtained by roasting with impregnating solution containing boric acid for 2 hours at 40 ℃, the impregnating solution contains 0.4 weight percent of boron (relative to the dry alumina carrier), the liquid/solid ratio is 2.0mL/g, drying the solid at 100 ℃ for 12 hours after impregnation, and roasting the solid at 550 ℃ for 4 hours to obtain the first solid product. In step S2, the potassium hydroxide solution contained 1.4% by weight of potassium, and the liquid/solid ratio was 2.0mL/g.
The platinum content in the catalyst B was 0.35 wt%, the tin content was 0.35 wt%, the potassium content was 1.4 wt%, the chlorine content was 1.3 wt%, and the boron content was 0.4 wt%.
Example 3
Catalyst C was prepared in the same manner as in example 1, except that step S1 was different. In this example, pt was impregnated before B, and the potassium content was increased, specifically:
taking spherical Sn-containing theta-alumina carrier, impregnating the spherical Sn-containing theta-alumina carrier for 2 hours at 40 ℃ by using impregnating solution containing chloroplatinic acid and hydrochloric acid, wherein the impregnating solution contains 0.35 weight percent of platinum and 1.0 weight percent of chlorine (relative to the dry alumina carrier), the liquid/solid ratio is 2.0mL/g, drying the solid at 100 ℃ for 12 hours after impregnation, roasting the solid at 550 ℃ for 4 hours, impregnating the solid product obtained by roasting with impregnating solution containing boric acid for 2 hours at 40 ℃, the impregnating solution contains 0.4 weight percent of boron (relative to the dry alumina carrier), the liquid/solid ratio is 2.0mL/g, drying the solid at 100 ℃ for 12 hours after impregnation, and roasting the solid at 550 ℃ for 4 hours to obtain the first solid product. In step S2, the potassium hydroxide solution contained 1.4% by weight of potassium, and the liquid/solid ratio was 2.0mL/g.
The platinum content in the catalyst C was 0.35 wt%, the tin content was 0.35 wt%, the potassium content was 1.4 wt%, the chlorine content was 1.0 wt%, and the boron content was 0.4 wt%.
Example 4
Catalyst D was prepared in the same manner as in example 1 except that in step S1, chloroplatinic acid, hydrochloric acid and boric acid were contained in the impregnation liquid containing 0.35% by weight of platinum, 1.0% by weight of hydrochloric acid and 0.4% by weight of boric acid (each relative to the dry alumina carrier, the same applies hereinafter).
In step S2, the impregnation solution used was a cesium hydroxide solution containing 1.3 wt% cesium (relative to the alumina carrier) to obtain a second solid product.
The catalyst contained 0.35 wt% of platinum, 0.35 wt% of tin, 1.3 wt% of cesium, 1.0 wt% of chlorine and 0.4 wt% of boron.
Example 5
Catalyst E was prepared in the same manner as in example 1 except that in step S1, the Sn-containing θ -alumina carrier b was used instead of the Sn-containing θ -alumina carrier a.
Comparative example 1
Catalyst DA was prepared in the same manner as in example 1, except that boric acid was not contained in the impregnation solution in step S1.
The catalyst contained 0.35 wt% of platinum, 0.35 wt% of tin, 1.3 wt% of potassium and 1.0 wt% of chlorine.
Comparative example 2
Catalyst DB was prepared in the same manner as in example 1 except that step S2 was not included, and the first solid product prepared in step S1 was directly subjected to oxychlorination and reduction.
The catalyst contained 0.35 wt% of platinum, 0.35 wt% of tin, 0.4 wt% of boron and 1.0 wt% of chlorine.
Test case
In a micro-reaction device, 2mL of catalyst is filled, mixed gas of hydrogen and propane is taken as raw material, and the feeding mass space velocity of propane is 9.0h at 615 ℃ and 0.21MPa (absolute pressure) -1 The molar ratio of hydrogen/propane was 0.33:1 for 20 hours, sampling every 1 hour, performing chromatographic analysis, calculating the conversion rate of propane and the selectivity of propylene, and testing the carbon content of the catalyst after the reaction. The conversion of propane dehydrogenation, the selectivity of propylene, the yield of propylene and the carbon content of the catalyst are shown in Table 1.
TABLE 1
Figure BDA0003334744920000131
Figure BDA0003334744920000141
From the above, the catalyst of the present invention has excellent conversion rate of raw material and selectivity of propylene when applied to the reaction of preparing olefin by dehydrogenating propane, and can effectively inhibit the generation of carbon deposit.
The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited to the specific details of the above embodiments, and various simple modifications can be made to the technical solution of the present invention within the scope of the technical concept of the present invention, and all the simple modifications belong to the protection scope of the present invention.
In addition, the specific features described in the above embodiments may be combined in any suitable manner, and in order to avoid unnecessary repetition, various possible combinations are not described further.
Moreover, any combination of the various embodiments of the invention can be made without departing from the spirit of the invention, which should also be considered as disclosed herein.

Claims (12)

1. A catalyst for preparing olefin by dehydrogenating low-carbon alkane, which comprises an alumina carrier and the following active components in content based on the dry weight of the alumina carrier:
Figure FDA0003334744910000011
the second metal component is selected from tin, germanium, lead, indium, gallium or thallium.
2. The catalyst of claim 1, wherein the catalyst comprises 0.1-1.5 wt% of the group viii metal, 0.1-1.5 wt% of the second metal component, 0.5-2.0 wt% of the group IA metal, 0.3-2.0 wt% of the halogen, and 0.1-3.0 wt% of the boron.
3. The catalyst of claim 1, wherein the catalyst comprises 0.1-0.5 wt.% of the group viii metal, 0.1-1.0 wt.% of the second metal component, 0.5-1.8 wt.% of the group IA metal, 0.5-1.8 wt.% of the halogen, and 0.1-2.0 wt.% of the boron.
4. The catalyst of claim 1, wherein the alumina support comprises theta alumina; the specific surface of the alumina carrier is 50-130m 2 Per gram, pore volume is 0.6-0.75 ml/g.
5. The catalyst according to claim 1, wherein the group viii metal is one or more of platinum, ruthenium, rhodium, palladium, iridium and osmium, preferably platinum;
the second metal component is tin;
the group IA metal is one or more of potassium, lithium, sodium, rubidium and cesium, preferably potassium;
the halogen is one or more of chlorine, bromine and fluorine, preferably chlorine.
6. A process for preparing the catalyst of any one of claims 1-5, the process comprising:
s1, carrying out first impregnation on an alumina carrier containing a second metal component by adopting a first impregnation liquid containing hydrochloric acid and a VIII metal compound, taking out a solid subjected to first impregnation, and carrying out first roasting to obtain a first solid product;
s2, contacting the first solid product with a second impregnating solution containing a group IA metal compound to carry out second impregnation, taking out the solid after the second impregnation and carrying out second roasting to obtain a second solid product;
wherein the boron has been impregnated on the first alumina support containing a second metal component prior to contacting the first solid product with the second impregnation liquid containing a group IA metal compound for a second impregnation;
s3, sequentially carrying out oxychlorination treatment and reduction treatment on the second solid product.
7. The method according to claim 6, wherein the group viii metal compound is selected from one or more of chloroplatinic acid, ammonium chloroplatinate and platinum chloride, preferably chloroplatinic acid;
the group IA metal compound is selected from one or more of hydroxide, nitrate and chloride of group IA metal, preferably one or more of potassium hydroxide, potassium nitrate and potassium chloride.
8. The method of claim 6, wherein the conditions of the first impregnation and the second impregnation each independently comprise: the temperature is 20-70 ℃ and the time is 2-6 hours;
the conditions of the oxychlorination treatment include: the temperature is 480-680 ℃ and the time is 1-10 hours, and the oxychlorination treatment is carried out in an atmosphere containing water, oxygen and chlorine-containing gas;
the conditions of the reduction treatment include: the temperature is 450-700 ℃ and the time is 0.5-20 hours.
9. The method of claim 6, wherein the alumina support containing the second metal component is prepared by a method comprising:
forming aluminum sol containing a second metal compound by adopting an oil ammonia column or a hot oil column drop ball to obtain aluminum oxide pellets, and performing third roasting on the aluminum oxide pellets at 450-1100 ℃; or alternatively, the process may be performed,
and (3) contacting the alumina carrier with a third impregnating solution containing a second metal compound for third impregnation, taking out a solid product after the third impregnation, and performing fourth roasting at 500-630 ℃.
10. The method of claim 9, wherein the second metal compound is selected from one or more of a chloride, bromide, nitrate, alkoxide, and organic complex of tin;
preferably, the second metal compound is selected from one or more of stannous bromide, stannous chloride, stannic chloride pentahydrate and tetrabutyltin.
11. A method for preparing olefin by dehydrogenating light alkane, comprising the following steps: contacting a lower alkane with the catalyst of any one of claims 1-5 to effect dehydrogenation.
12. The method of claim 11, wherein the dehydrogenation reaction conditions comprise: the temperature is 400-750 ℃, the pressure is 0.1-1.0MPa, and the mass airspeed of the low-carbon alkane is 0.1-20h -1 ；
The lower alkane is selected from C 3 ～C 5 Preferably propane, pentane, n-butane or isobutane.
CN202111290648.3A 2021-11-02 2021-11-02 Catalyst for preparing olefin by dehydrogenating low-carbon alkane and preparation method and application thereof Pending CN116060045A (en)

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