CN117065785A - Catalyst, preparation method and application thereof - Google Patents

Catalyst, preparation method and application thereof Download PDF

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Publication number
CN117065785A
CN117065785A CN202311352248.XA CN202311352248A CN117065785A CN 117065785 A CN117065785 A CN 117065785A CN 202311352248 A CN202311352248 A CN 202311352248A CN 117065785 A CN117065785 A CN 117065785A
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catalyst
groups
mixture
temperature
hours
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CN117065785B (en
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陈康
孔祥明
张郁葱
王怡捷
田宇
张宏科
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Wanhua Chemical Group Co Ltd
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Wanhua Chemical Group Co Ltd
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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
    • B01J29/00—Catalysts comprising molecular sieves
    • B01J29/03—Catalysts comprising molecular sieves not having base-exchange properties
    • B01J29/035—Microporous crystalline materials not having base exchange properties, such as silica polymorphs, e.g. silicalites
    • B01J29/0352—Microporous crystalline materials not having base exchange properties, such as silica polymorphs, e.g. silicalites containing iron group metals, noble metals or copper
    • B01J29/0354—Noble metals
    • 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
    • B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
    • B01J37/0009—Use of binding agents; Moulding; Pressing; Powdering; Granulating; Addition of materials ameliorating the mechanical properties of the product catalyst
    • B01J37/0018—Addition of a binding agent or of material, later completely removed among others as result of heat treatment, leaching or washing,(e.g. forming of pores; protective layer, desintegrating by heat)
    • 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
    • B01J8/00—Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes
    • B01J8/02—Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes with stationary particles, e.g. in fixed beds
    • B01J8/0285—Heating or cooling the reactor
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C11/00—Aliphatic unsaturated hydrocarbons
    • C07C11/02—Alkenes
    • C07C11/06—Propene
    • 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
    • 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
    • B01J2208/00—Processes carried out in the presence of solid particles; Reactors therefor
    • B01J2208/00008—Controlling the process
    • B01J2208/00017—Controlling the temperature
    • B01J2208/00389—Controlling the temperature using electric heating or cooling elements
    • 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
    • B01J2229/00—Aspects of molecular sieve catalysts not covered by B01J29/00
    • B01J2229/10—After treatment, characterised by the effect to be obtained
    • B01J2229/18—After treatment, characterised by the effect to be obtained to introduce other elements into or onto the molecular sieve itself
    • B01J2229/186—After treatment, characterised by the effect to be obtained to introduce other elements into or onto the molecular sieve itself not in framework positions
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C2529/00—Catalysts comprising molecular sieves
    • C07C2529/03—Catalysts comprising molecular sieves not having base-exchange properties
    • C07C2529/035—Crystalline silica polymorphs, e.g. silicalites
    • 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

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  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Catalysts (AREA)

Abstract

The invention relates to the field of catalysts, in particular to a catalyst for producing propylene by propane dehydrogenation, a preparation method and application thereof, wherein the preparation method of the catalyst comprises the following steps: providing a first mixture comprising an S-1 all-silicon molecular sieve, a second silicon source, a second templating agent, and an active metal solution; aging the first mixture at the temperature of-25-0 ℃ to obtain a second mixture; performing second crystallization treatment on the second mixture to obtain a crystallized product; and forming and roasting the third mixture comprising the crystallized product to obtain the catalyst. The molecular sieve catalyst of the embodiment of the invention can be used for producing propylene by Propane Dehydrogenation (PDH), and compared with the traditional PDH catalyst, the molecular sieve catalyst can simplify the regeneration process of the traditional propane dehydrogenation catalyst, reduce the carbon deposition content and prolong the single-cycle service time of the catalyst.

Description

Catalyst, preparation method and application thereof
Technical Field
The present invention relates to a catalyst, and more particularly, to a catalyst for producing propylene by dehydrogenation of Propane (PDH).
Background
Propylene is an important chemical raw material. The existing process method for producing propylene has a plurality of processes, wherein the process for preparing propylene by dehydrogenating propane has the advantages of relatively simple flow, high propylene selectivity, better product singleness, environmental protection, low comprehensive cost and the like. Therefore, industrial application of propane dehydrogenation has become more and more widespread.
The Oleflex process developed by UOP is a propane dehydrogenation process that has been currently implemented for large-scale industrial applications. In the prior art, the process adopts a four-reverse series moving bed reactor, and the catalyst can continuously react and be removed for regeneration in the process. However, the catalyst is worn to a certain extent by the transmission of different reactors, and the screen is easy to be blocked after long-term operation, which is not beneficial to the stable operation of the device. Meanwhile, as the catalyst used in the process is a platinum catalyst prepared by a traditional impregnation method, chlorine injection is needed in the regeneration process, so that the risk of the process and the complexity of the regeneration operation are increased.
On the other hand, as the reactors are in a four-reverse series connection mode, in order to maintain the reaction temperature in each reactor, the process adopts a graded heating mode for materials, and a set of heating units are respectively arranged among the reactors, so that the materials are graded heated. However, the heating unit heats the material before the inlet of each reactor, but a certain temperature difference (40-65 ℃) still exists in the single reactor. And the reaction time is prolonged along with the transfer of the catalyst between the reactors, and the activity and propylene selectivity of the catalyst are reduced to different degrees.
Disclosure of Invention
To overcome at least one of the above-described drawbacks of the prior art, in a first aspect, an embodiment of the present invention provides a method for preparing a catalyst, comprising:
providing a first mixture comprising an S-1 all-silicon molecular sieve, a second silicon source, a second templating agent, and an active metal solution;
aging the first mixture at the temperature of-25-0 ℃ to obtain a second mixture;
performing second crystallization treatment on the second mixture to obtain a crystallized product; and
and forming and roasting the third mixture comprising the crystallized product for the second time to obtain the catalyst.
In a second aspect, an embodiment of the present invention provides a catalyst prepared by the above-described preparation method.
In a third aspect, an embodiment of the present invention provides a propylene production process, including dehydrogenating propane to produce propylene under the action of the above catalyst.
The catalyst of the embodiment of the invention can be used for a process for preparing propylene by propane dehydrogenation, can simplify the regeneration process of the traditional propane dehydrogenation catalyst (chlorine injection is not needed in the regeneration process), reduce the carbon deposition content and prolong the single-cycle service time of the catalyst.
Drawings
The drawings are only for purposes of illustrating particular embodiments and are not to be construed as limiting the invention. Wherein:
FIG. 1 is a graph showing the conversion rate over time of the catalysts of example 1, example 2 and comparative example 1 of the present invention after several cycles of propane dehydrogenation reaction-in-situ carbon burn regeneration under the same experimental conditions;
FIG. 2 is a schematic structural view showing an apparatus for carrying out a conventional adiabatic propane dehydrogenation reaction according to application example 2 of the present invention;
the reference numerals are explained as follows:
10. a preheating furnace; 11. a first temperature controller; 20. a fixed bed reactor; 21. and a second temperature controller.
Detailed Description
Exemplary embodiments that embody features and advantages of the present invention will be described in detail in the following description. It will be understood that the invention is capable of various modifications in various embodiments, all without departing from the scope of the invention, and that the description is intended to be illustrative in nature and not to be limiting.
An embodiment of the present invention provides a method for preparing a catalyst, including:
providing a first mixture comprising an S-1 all-silicon molecular sieve (all-silicon Silicate-1 molecular sieve), a second silicon source, a second templating agent, and an active metal solution;
aging the first mixture at the temperature of-25-0 ℃ to obtain a second mixture;
carrying out second crystallization treatment on the second mixture to obtain a crystallized product; and
and forming and second roasting the third mixture comprising the crystallized product to obtain the catalyst.
In one embodiment, the S-1 all-silicon molecular sieve can be prepared by prior art techniques, such as hydrothermal crystallization.
In one embodiment, the S-1 all-silicon molecular sieve is prepared by a process comprising: performing first crystallization treatment and first roasting treatment on the initial mixture; wherein the initial mixture comprises a first silicon source, a first base compound, a first templating agent, and water.
In one embodiment, the initial mixture is sequentially subjected to a first crystallization process, a washing process, a drying process, and a first calcination process to obtain the S-1 all-silicon molecular sieve.
In one embodiment, the temperature of the first crystallization treatment may be 165 to 195 ℃, such as 170 ℃, 175 ℃, 180 ℃, 185 ℃, 190 ℃; the time may be 24 to 72 hours, for example 30, 35, 36, 38, 40, 42, 45, 48, 50, 54, 60, 64, 65, 68, 70 hours.
In one embodiment, the temperature of the first firing treatment may be 520 to 600 ℃, such as 550 ℃, 580 ℃; the time may be 4 to 16 hours, for example 6 hours, 8 hours, 10 hours, 12 hours, 15 hours.
In one embodiment, the first base compound may be one, two or more of sodium hydroxide, potassium hydroxide, calcium hydroxide, barium hydroxide, ammonia.
In one embodiment, the first silicon source may be one, two or more of ethyl orthosilicate, sodium silicate, white carbon black, silica sol.
In one embodiment, the first templating agent comprises one, two or more of tetraethylammonium bromide, tetrapropylammonium bromide, tetrabutylammonium bromide, tetrapropylammonium hydroxide, ethylamine, butylamine.
In one embodiment, the mass ratio of the components in the initial mixture is: the first alkali compound is a first silicon source, the first template agent (M) is water= (0.03-0.15), the first alkali compound is 1.0 (0.05-0.5), and the first template agent is 1-4.5.
In one embodiment, the first mixture further comprises a second base compound, and the S-1 all-silicon molecular sieve, the second silicon source, the second template, the second base compound, and the active metal solution may be mixed and then thoroughly stirred to obtain the first mixture.
In one embodiment, the second silicon source may be one, two or more of ethyl orthosilicate, sodium silicate, white carbon black, silica sol.
In one embodiment, the second templating agent comprises one, two or more of tetraethylammonium bromide, tetrapropylammonium bromide, tetrabutylammonium bromide, tetrapropylammonium hydroxide, ethylamine, butylamine.
In one embodiment, the second base compound may be one, two or more of sodium hydroxide, potassium hydroxide, calcium hydroxide, barium hydroxide, ammonia.
In one embodiment, the active metal in the active metal solution may be elemental platinum and the solvent may be water.
In one embodiment, the active metal solution is prepared from active metal compound, solvent and auxiliary agent, wherein the solvent can be water; further, the raw materials for preparing the active metal solution comprise active metal compoundsAnd/or [ Pt (NH) 3 ) 2 (NO 2 ) 2 ]And an auxiliary agent->、/>、C 10 H 12 FeN 2 Na 2 O 8 、MgSO 4 、MgCl 2 、KCl、K 2 SO 4 、La(NO 3 ) 3 、InCl 3 、LaCl 3 、YCl 3 、CeCl 3 One or more of the following.
In one embodiment, the mass ratio of the S-1 all-silicon molecular sieve, the second silicon source, the second template agent, the second base compound, the active metal compound, and the solvent (water) is: s-1 full-silicon molecular sieve, second silicon source, second template agent, second alkali compound, active metal compound, water=1 (0.1-0.5), 0.05-0.5, 0.03-0.15, 0.003-0.5 and 1-4.5.
In one embodiment, the temperature of the aging treatment may be from-25 to 0 ℃, preferably from-25 to-15 ℃, more preferably from-25 to-18 ℃, still more preferably from-22 to-18 ℃, still more preferably from-21 to-19 ℃, such as from-18 to-15 ℃, from-12 to-10 ℃, from-8 ℃, from-5 to-2 ℃; the aging process may be performed in an ice chest, for example, by placing the first mixture in an ice chest for aging.
In one embodiment, the time of the aging treatment may be 0.5 to 72 hours, for example 1 hour, 2 hours, 5 hours, 8 hours, 10 hours, 12 hours, 20 hours, 24 hours, 30 hours, 36 hours, 40 hours, 48 hours, 50 hours, 55 hours, 60 hours, 65 hours, 70 hours.
In one embodiment, the second crystallization process may be performed in a muffle furnace, for example, a reaction vessel containing the second mixture (frozen mixture) may be placed in the muffle furnace, programmed to heat, and the second crystallization process performed at a temperature.
In one embodiment, the temperature of the second crystallization process may be 150 to 195 ℃, such as 155 ℃, 160 ℃, 165 ℃, 170 ℃, 175 ℃, 180 ℃, 185 ℃, 190 ℃; during the second crystallization treatment, the temperature of the system may be raised to 150 to 195℃at a rate of 1 to 10℃per minute, for example, 2℃per minute, 3℃per minute, 5℃per minute, 6℃per minute, 8℃per minute.
In one embodiment, the second crystallization process may be performed for a period of 16 to 72 hours, for example, 20 hours, 24 hours, 30 hours, 36 hours, 40 hours, 48 hours, 50 hours, 55 hours, 60 hours, 65 hours, 70 hours.
In one embodiment, after the second crystallization treatment is finished, the obtained product is subjected to suction filtration, drying and other treatments to obtain a crystallized product. Mixing the crystallized product with a binder to obtain a third mixture; further, the third mixture may include kaolin.
In one embodiment, the third mixture is shaped and subjected to a second calcination treatment to produce a molecular sieve catalyst having a nano-alloy structure with a uniform distribution of active components.
In one embodiment, the temperature of the second firing treatment is 500 to 600 ℃, such as 520 ℃, 550 ℃, 560 ℃, 580 ℃; the time is 4 to 12 hours, such as 5 hours, 6 hours, 8 hours and 10 hours.
An embodiment of the present invention provides a catalyst that can be prepared by a freeze-thaw in situ secondary crystallization process, for example, that can be prepared by the above-described preparation process.
The catalyst of one embodiment of the invention is a molecular sieve catalyst with core-shell active metal distribution.
The catalyst of one embodiment of the invention has high carbon deposition resistance and catalytic stability.
One embodiment of the invention provides a propylene production process, which comprises the step of carrying out propane dehydrogenation treatment under the action of the catalyst to obtain propylene.
In one embodiment, the propylene production process is a continuous catalytic propane dehydrogenation process.
In one embodiment, the propane dehydrogenation process is performed using one or more (e.g., two) fixed bed reactors, and further, the fixed bed reactors have a heating function.
In one embodiment, the use of a fixed bed reactor with heating function can keep the reaction process at a constant temperature; further, the fixed bed reactor may be an existing apparatus, for example, the fixed bed reactor may be an electric heating reactor having a heating function itself.
In one embodiment, the propylene production process is carried out in a propane dehydrogenation continuous reaction system comprising two or more electrically heated reactors (fixed bed reactors) in parallel.
In one embodiment, the two processes of propane dehydrogenation and in-situ catalyst regeneration can be performed in different reactors in the same time period; the two technological processes of dehydrogenation reaction of propane and in-situ regeneration of catalyst can be sequentially carried out in the same reactor; the materials such as hydrocarbon compounds, air, hydrogen and the like required by each process can be switched through the valve, so that continuous operation of propane dehydrogenation can be realized.
In one embodiment, one reactor may be used to perform the propane dehydrogenation reaction while the other reactor is used to perform catalyst regeneration and temperature rise preparation during operation. After the reaction of the reactor is finished, the air inlet valve is switched, and the propane feed is switched to other reactors containing the regenerated and reduced catalyst for continuous reaction. Further, the propane raw material can be introduced into a reactor containing a regenerated and reduced fresh catalyst for catalytic dehydrogenation reaction; at the same time, the rest standby reactors which do not participate in the reaction are subjected to the processes of catalyst regeneration and temperature rise preparation, and before the standby reactors are switched to the reaction operation reactor, parameters such as pressure, temperature and the like in the standby reactors are adjusted so as to keep the same operation parameters as the reaction operation stage, and then the on-line switching operation is performed. Finally, a continuous dehydrogenation production process system which is 'same-open and same-standby' and is formed by connecting two or more electric heating reactors in parallel is formed.
In one embodiment, the temperature at which the propane dehydrogenation reaction is catalyzed may be 560 to 630 ℃, such as 570 ℃, 580 ℃, 590 ℃, 600 ℃, 610 ℃, 620 ℃.
In one embodiment, the pressure at which the propane dehydrogenation reaction is catalyzed may be in the range of-0.01 to 0.05MPa, for example 0.01MPa, 0.02MPa, 0.03MPa.
In one embodiment, the space velocity for catalyzing the propane dehydrogenation reaction can be 790 to 2400 hours -1 For example 800h -1 、1000h -1 、1200h -1 、1500h -1 、1800h -1 、2000h -1 、2200h -1 The method comprises the steps of carrying out a first treatment on the surface of the The continuous reaction time may be 9 to 170 hours, for example 10 hours, 20 hours, 50 hours, 60 hours, 80 hours, 100 hours, 120 hours, 150 hours, 160 hours.
In one embodiment, in the catalytic propane dehydrogenation reaction, the hydrogen-to-hydrocarbon ratio may be in the range of 0 to 0.5, for example 0.1, 0.2, 0.3, 0.4.
In one embodiment, the catalyst in situ regeneration process comprises a post-reaction nitrogen purge stage, an air-in or air/nitrogen on-line carbon deposition firing stage, a nitrogen purge displacement stage, an air-in hydrogen reduction stage, and a warm-up stage, wherein the warm-up is used to prepare for the next cycle of propane dehydrogenation reaction.
In one embodiment, during in situ catalyst regeneration, the purge displacement medium may be nitrogen and the space velocity may be 450 to 3000 hours -1 For example 500h -1 、800h -1 、1000h -1 、1500h -1 、2000h -1 、2500h -1 The method comprises the steps of carrying out a first treatment on the surface of the The purge time may be 0.5 to 2 hours, for example 1 hour, 1.5 hours.
In one embodiment, in the in-situ regeneration process of the catalyst, the carbon burning medium is air or air/nitrogen mixed gas, the oxygen content can be 5-21 vol%, the temperature can be 400-550 ℃, and the carbon burning time can be 1.5-6 h.
In one embodiment, during in situ regeneration of the catalyst, the reducing medium of the catalyst is hydrogen, and the reducing temperature may be 350 to 590 ℃, such as 380 ℃, 400 ℃, 450 ℃, 500 ℃, 550 ℃; airspeed may be 390 to 1500 hours -1 For example 400h -1 、500h -1 、800h -1 、1000h -1 、1200h -1 The method comprises the steps of carrying out a first treatment on the surface of the The reduction time may be 1.5 to 4 hours, for example 2 hours, 2.5 hours, 3 hours, 3.5 hours.
Compared with the traditional PDH catalyst, the molecular sieve catalyst of the embodiment of the invention has the advantages of greatly improved regeneration stability and anti-carbon deposition performance, long service life, high propylene selectivity and the like.
The temperature difference inside the reactor or the temperature drop of the catalyst bed of the prior art can be attributed to the "congenital defect" of the adiabatic reactor, which is difficult to avoid by optimizing the process alone. In contrast, the constant-temperature fixed bed reactor has the advantages of constant reaction temperature, simple equipment, strong operability and the like, and has higher selectivity to propylene. However, the constant temperature fixed bed reactor is very demanding for the catalyst, which first requires the catalyst to have excellent catalytic activity and selectivity, and requires the catalyst to have excellent stability and anti-carbon deposition ability. However, the catalysts used in the prior art all need to be frequently transferred, baked, reheated and the like, which obviously does not accord with the characteristics of the constant-temperature fixed bed reactor.
According to the propylene production process of one embodiment of the invention, by adopting the catalyst prepared in situ and combining with the constant-temperature electric heating reactor, simplification of the conventional propane dehydrogenation catalyst regeneration process (chlorine injection is not required in the regeneration process) and low-cost continuous operation of the catalytic propane dehydrogenation process can be realized, the lower reaction temperature and the higher propylene selectivity are shown compared with the conventional process, and the product yield is kept unchanged; therefore, the energy consumption and the unit propane consumption in the propylene production process by the propane dehydrogenation can be effectively reduced, the economic benefit is improved, and the propylene production process has the characteristics of low energy consumption and low material consumption.
The catalyst and its application according to one embodiment of the present invention will be further described with reference to the accompanying drawings and specific examples. The feed and product composition in the reaction evaluation experiment are all measured by gas chromatography analysis, correction is carried out by utilizing carbon conservation, and the calculation methods of the propane conversion rate and the propylene selectivity are respectively shown in formulas (1) and (2).
Example 1
(1) 329.2g of deionized water and 80g of ethyl orthosilicate are weighed and added into a beaker, and the mixture is stirred uniformly, and the rotating speed is controlled to be 300r/min; 4.65g NaOH and 17.05g TPAOH (tetrapropylammonium bromide) were weighed into the beaker and stirred at room temperature for 30min to give an initial mixture.
(2) The initial mixture was transferred to a stainless steel autoclave and the autoclave was placed in an oven for crystallization (first crystallization treatment), wherein the crystallization temperature was 170 ℃ and the crystallization time was 36h. After crystallization, washing the sample, drying the sample at 120 ℃ for 12 hours, and roasting the sample at 550 ℃ for 6 hours to obtain the S-1 all-silicon molecular sieve.
(3) 100g of the prepared S-1 all-silicon molecular sieve, 297.5g of deionized water and 21.8g of tetraethoxysilane are weighed and added into a 500mL beaker, and are uniformly stirred, and the rotating speed is controlled to be 300r/min; weigh 0.73g、1.52g0.32g La (NO) 3 ) 3 Adding into the beaker, mixing and stirring uniformly; 3.72g NaOH and 12.05g tetrapropylammonium bromide were weighed into the beaker and stirring was continued for 2. 2h to obtain a first mixture.
(4) Transferring the first mixture into a stainless steel reaction kettle with a polytetrafluoroethylene lining, transferring the reaction kettle into a freezer for refrigeration and aging, setting the aging temperature to be minus 20 ℃, and aging the first mixture in a low-temperature environment of minus 20 ℃ for 72 hours to obtain a frozen mixture (second mixture).
(5) And (3) placing the reaction kettle containing the second mixture into a muffle furnace, setting a program to perform temperature programming, setting the heating rate to be 2 ℃/min, setting the temperature to be 180 ℃, and maintaining the temperature for 72h to perform second crystallization treatment.
(6) After the autoclave was cooled to room temperature, the slurry was removed and washed with deionized water and suction filtered to neutral pH. Drying the crystallized product after suction filtration in an oven at 120 ℃ for 12 hours; and mixing the obtained product with the kaolin as a binder, molding, and roasting the molded product in a muffle furnace at 550 ℃ for 6 hours to obtain the molecular sieve catalyst.
Example 2
The S-1 all-silicon molecular sieve is prepared by adopting the same raw materials and processes as in the steps (1) and (2) of the example 1.
(3) 100g of the prepared S-1 all-silicon molecular sieve, 297.5g of deionized water and 21.8g of tetraethoxysilane are weighed and added into a 500mL beaker, and are uniformly stirred, and the rotating speed is controlled to be 300r/min; weigh 0.62g、1.89g0.27g YCl 3 Adding into the beaker, mixing and stirring uniformly; 3.57g NaOH and 11.85g tetrapropylammonium bromide were weighed into a beaker and stirred for 2 hours to obtain a first mixture.
(4) Transferring the first mixture into a stainless steel reaction kettle with a polytetrafluoroethylene lining, transferring the reaction kettle into a freezer for refrigeration and aging, setting the aging temperature to be minus 20 ℃, and aging the first mixture in a low-temperature environment of minus 20 ℃ for 48 hours to obtain a frozen mixture (second mixture).
(5) And (3) placing the reaction kettle containing the second mixture into a muffle furnace, setting a program to perform temperature programming, setting the heating rate to be 2 ℃/min, setting the temperature to be 180 ℃, and maintaining the temperature for 72h to perform second crystallization treatment.
(6) After the autoclave was cooled to room temperature, the slurry was removed and washed with deionized water and suction filtered to neutral pH. Placing the suction-filtered sample in an oven and drying at 120 ℃ for 12 hours; and mixing the obtained product with the kaolin as a binder, molding, and roasting the molded product in a muffle furnace at 550 ℃ for 6 hours to obtain the molecular sieve catalyst.
Example 3
This example uses essentially the same starting materials and process as example 1 to prepare the catalyst, except that: the aging temperature in the step (4) is-25 ℃.
Example 4
This example uses essentially the same starting materials and process as example 1 to prepare the catalyst, except that: the aging temperature in the step (4) is-10 ℃.
Example 5
This example uses essentially the same starting materials and process as example 1 to prepare the catalyst, except that: the aging temperature in the step (4) is-15 ℃.
Example 6
This example uses essentially the same starting materials and process as example 1 to prepare the catalyst, except that: the aging temperature in the step (4) is-5 ℃.
Example 7
This example uses essentially the same starting materials and process as example 1 to prepare the catalyst, except that: the aging temperature in the step (4) is 0 ℃.
Comparative example 2
The catalyst was prepared using essentially the same starting materials and process as in example 1, except that: the aging temperature in step (4) is 25 ℃.
Comparative example 3
The catalyst was prepared using essentially the same starting materials and process as in example 1, except that: the low temperature aging process of step (4) is not performed.
Application example 1
The catalysts of examples 1-2 and comparative examples 1-3 were used to perform catalytic dehydrogenation isothermal reaction of propane under the same reaction conditions by means of an electrically heated fixed bed reactor, and the long-period reaction stability and anti-carbon deposition performance of the catalysts were evaluated. Wherein, the reaction conditions are as follows: 3mL of catalyst loading, 6mL of inert porcelain ball, 20mL/min of hydrogen flow, 40mL/min of propane flow, 600 ℃ of reaction temperature and 0.05MPa of reaction pressure.
The relevant test results are shown in table 1. The catalyst of comparative example 1 is a traditional industrial propane dehydrogenation noble metal catalyst, and the catalyst model is DEH-24 of UOP.
TABLE 1 results of long-period reaction tests for the catalysts of examples 1-2, comparative examples 1-3
It can be seen from table 1 that the catalyst prepared in examples 1 and 2 showed a decrease in propane conversion within 1.5 percent after continuous propane dehydrogenation for 52 hours under exactly the same reaction conditions; whereas the activity of the conventional commercial catalyst of comparative example 1 was significantly reduced and the activity was lost. Therefore, the catalyst of the embodiment of the invention has higher catalytic stability compared with the traditional industrial catalyst. Meanwhile, the results in table 1 also show that the catalyst of the present invention can exhibit more excellent anti-carbon deposition performance than the conventional propane dehydrogenation catalyst.
Further, example 1 is different from comparative examples 2, 3 in that: the ageing temperature for example 1 was-20 ℃, the ageing temperature for comparative example 2 was 25 ℃, and comparative example 3 was not aged. As can be seen from Table 1, the propane conversion of example 1 was significantly higher than that of comparative examples 2, 3, and the carbon deposition amount was significantly lower than that of comparative examples 2, 3. Thus, the performance of the catalyst obtained by aging the first mixture at a low temperature of-20 ℃ is superior to that of the catalyst obtained by aging at normal temperature and without aging.
The catalyst samples of examples 1-7 and comparative examples 1-3 were characterized for Pt dispersity by CO-pulse adsorption experiments using a Micromeritics AutoChem ii 2920 chemisorber. Pt dispersity was calculated by the adsorption amount of CO, the catalyst sample was reduced in situ with hydrogen gas at 470 ℃ for 1h (purity 99.99%,20 ml/min) in advance, then switched to purging with He at 520 ℃ for 1h (99.99%, 20 ml/min), and then the temperature was lowered to 50 ℃ for CO pulse adsorption. 0.1ml of a 5% CO+95% He mixture was pulsed into the reactor with an interval of 4min until adsorption was saturated. The volume of the catalyst sample that adsorbed CO was measured with TCD. The Pt dispersity is calculated by the amount of CO adsorbed, assuming that CO dissociates and adsorbs on Pt, and that one Pt active site is per CO molecule. The results are shown in Table 2.
TABLE 2 test results of Pt dispersity for the catalysts of examples 1-7, comparative examples 1-3
As can be seen from table 2, the Pt dispersion degree of comparative example 1 (industrial conventional supported catalyst) was the lowest, which is only 55.2%, mainly because the conventional supported catalyst was prepared by conventional impregnation, and the active metal Pt was significantly agglomerated during calcination after impregnation to form larger platinum metal particles, so that the Pt dispersion degree was lower.
In contrast, the catalyst samples of examples 1-4 and comparative examples 2 and 3, because of the in-situ synthesis method, have a relatively higher Pt dispersity because the active metal Pt can be better distributed on the surface of the molecular sieve than the conventional impregnation method. In addition, the catalyst samples prepared in the embodiments 1-4 of the present invention show higher Pt dispersity, which is mainly caused by the low-temperature aging process, the low-temperature environment can slow down the diffusion rate of molecules in the gel, pt and corresponding auxiliary agents can be distributed more uniformly in the system after long-time slow diffusion, the Pt active metal components can be well distributed on the outer layer of the molecular sieve by combining the secondary crystallization process, and during the temperature programming roasting process, pt and the auxiliary agents form a nano alloy structure, so that the catalyst samples show excellent Pt dispersity, which is also the reason for better stability and good regeneration performance.
Further, examples 1, 3 to 7 are different in that: the aging temperatures in step (4) are different. As can be seen from the results of Table 2, the Pt dispersion degree of each catalyst prepared at the aging temperature in the range of-10 to 0℃is not greatly different, while the Pt dispersion degree of the catalyst prepared at the aging temperature in the range of-25 to-15℃is significantly higher than that of the catalyst prepared at the aging temperature in the range of-10 to 0℃and the Pt dispersion degree of the catalyst prepared at the aging temperature of-20℃and-25℃is higher than that of the catalyst prepared at-15 ℃. Thus, the aging temperature of the first mixture according to one embodiment of the present invention is preferably-25 to-15 ℃, more preferably-25 to-18 ℃, still more preferably-22 to-18 ℃, still more preferably-21 to-19 ℃, and most preferably-20 ℃.
In addition, the catalysts of examples 1-2 and comparative example 1 were subjected to continuous in-situ carbon burning regeneration experiments by using the same experimental equipment, specifically: firstly, nitrogen purging and replacement are carried out on the reacted reactor, then the temperature is raised to 520 ℃, a proper amount of oxygen is introduced to carry out in-situ carbon burning regeneration on the catalyst, the regeneration operation is completed after 4 hours, the next round of catalyst reduction reaction process is carried out, and the test result is shown in figure 1. The catalyst prepared in the embodiment 1-2 of the invention does not need chlorine injection in the regeneration process, and the result of FIG. 1 shows that the reaction activity of the catalyst is still maintained at a higher level after four-cycle reaction-regeneration experiments; whereas the activity of the conventional catalyst of comparative example 1 was significantly reduced. This is mainly due to the fact that in the conventional supported catalysts, the active metals gradually agglomerate during the reaction, losing their activity, and therefore the regeneration process requires the "chlorine injection" to redisperse the active components. The molecular sieve catalyst prepared by the in-situ synthesis method can well fix active metal on a molecular sieve framework or a framework structure, so that the active metal can keep a good dispersion state in the reaction process, and the aggregation and agglomeration phenomenon is avoided, thereby achieving the purposes of no need of chlorine injection and simplification of the operation flow of a regeneration process.
Application example 2
Catalytic dehydrogenation of propane was carried out by means of an electrically heated fixed bed reactor using the catalyst of example 1. The temperature is controlled by an electric heater in the reaction process, and the constant-temperature reaction is kept. The reaction conditions are as follows: the catalyst loading is 3mL, the inert porcelain ball is 6mL, the hydrogen flow is 20mL/min, the propane flow is 40mL/min, and the reaction pressure is 0.05MPa.
The relevant test results are shown in table 3.
Comparative example 1 was used
The device of fig. 2 is adopted to simulate the catalytic reaction process of a traditional adiabatic reactor, wherein a preheating furnace 10 is communicated with a fixed bed reactor 20, and a first temperature controller 11 is arranged on a pipeline outside the preheating furnace 10 and used for monitoring the temperature at the outlet of the preheating furnace 10; a second temperature controller 21 is provided outside the fixed bed reactor 20 for monitoring the temperature inside the fixed bed reactor 20.
The reaction materials are fed into a preheating furnace 10 for heating, and the fixed bed reactor 20 does not perform heating operation; after the outlet temperature of the preheating furnace 10 reached the set point of 594 ℃, propane was introduced into a fixed bed reactor containing the conventional industrial catalyst of comparative example 1 to perform catalytic propane dehydrogenation reaction. Except for the above reaction scheme and the set temperature, the conditions such as space velocity and hydrogen-hydrocarbon ratio remained the same as in application example 2. The relevant test results are shown in table 3.
TABLE 3 propane dehydrogenation test results for application example 2 and application comparative example 1
The test results of the constant temperature fixed bed PDH process of the present invention of application example 2 and the conventional adiabatic reaction process of application comparative example 1 are shown in table 3. As can be seen from the reaction results, the reaction temperature used in the constant temperature process of application example 2 was lower than that of the conventional adiabatic reaction process by 9℃under the condition of ensuring the consistent propylene yield. Lower reaction temperatures mean lower plant energy consumption, for example 75 ten thousand tons per year PDH project, with a predicted energy savings of 3.4MW. In addition, as can be seen from the reaction test results, under the condition of the same propylene yield, the process of the application example 2 can realize higher propylene selectivity, which can reach 94.1 percent, and is 3.9 percent higher than that of the traditional process method, the unit consumption of converted propane can be reduced by 45kg, and the unit consumption of converted propane can be reduced by 225 yuan/t propylene.
Therefore, compared with the traditional process, the constant temperature fixed bed reaction process adopting the specific catalyst in the embodiment of the invention can obtain the same (or similar) propylene yield with lower reaction temperature and higher propylene selectivity, thereby effectively reducing the energy consumption and the unit propane consumption in the propylene production process of propane dehydrogenation.
Unless otherwise defined, all terms used herein are intended to have the meanings commonly understood by those skilled in the art.
The described embodiments of the present invention are intended to be illustrative only and not to limit the scope of the invention, and various other alternatives, modifications, and improvements may be made by those skilled in the art within the scope of the invention, and therefore the invention is not limited to the above embodiments but only by the claims.

Claims (10)

1. A method for preparing a catalyst, comprising:
providing a first mixture comprising an S-1 all-silicon molecular sieve, a second silicon source, a second templating agent, and an active metal solution;
aging the first mixture at the temperature of-25-0 ℃ to obtain a second mixture;
performing second crystallization treatment on the second mixture to obtain a crystallized product; and
and forming and roasting the third mixture comprising the crystallized product for the second time to obtain the catalyst.
2. The method according to claim 1, wherein the aging treatment is carried out for 0.5 to 72 hours; and/or the number of the groups of groups,
the active metal in the active metal solution comprises platinum element.
3. The method of claim 1, wherein the S-1 all-silicon molecular sieve is prepared by a process comprising: performing first crystallization treatment and first roasting treatment on the initial mixture; the initial mixture includes a first silicon source, a first base compound, a first templating agent, and water.
4. A method according to claim 3, wherein the initial mixture comprises the following components in mass ratio: the first alkali compound is a first silicon source, the first template agent is water= (0.03-0.15), 1.0 (0.05-0.5), and 1-4.5; and/or the number of the groups of groups,
the first alkali compound comprises one, two or more of sodium hydroxide, potassium hydroxide, calcium hydroxide, barium hydroxide and ammonia water; and/or the number of the groups of groups,
the first silicon source comprises one, two or more of tetraethoxysilane, sodium silicate, white carbon black and silica sol; and/or the number of the groups of groups,
the first template agent comprises one, two or more of tetraethylammonium bromide, tetrapropylammonium bromide, tetrabutylammonium bromide, tetrapropylammonium hydroxide, ethylamine and butylamine.
5. The preparation method according to claim 1, wherein the first mixture comprises a second alkali compound, the preparation raw materials of the active metal solution comprise an active metal compound and a solvent, and the mass ratio of the S-1 all-silicon molecular sieve to the second silicon source to the second template to the second alkali compound to the active metal compound to the solvent is 1 (0.1-0.5): 0.05-0.5): 0.03-0.15): 0.003-0.5): 1-4.5; and/or the number of the groups of groups,
the second silicon source comprises one, two or more of tetraethoxysilane, sodium silicate, white carbon black and silica sol; and/or the number of the groups of groups,
the second template agent comprises one, two or more of tetraethylammonium bromide, tetrapropylammonium bromide, tetrabutylammonium bromide, tetrapropylammonium hydroxide, ethylamine and butylamine.
6. The method according to claim 5, wherein the raw materials for preparing the active metal solution includeAnd/or [ Pt (NH) 3 ) 2 (NO 2 ) 2 ]And->、/>、C 10 H 12 FeN 2 Na 2 O 8 、MgSO 4 、MgCl 2 、KCl、K 2 SO 4 、La(NO 3 ) 3 、InCl 3 、LaCl 3 、YCl 3 、CeCl 3 One or more of the following; and/or the number of the groups of groups,
the second alkali compound comprises one, two or more of sodium hydroxide, potassium hydroxide, calcium hydroxide, barium hydroxide and ammonia water.
7. The method according to claim 1, wherein the temperature of the second crystallization treatment is 150 to 195 ℃; and/or the number of the groups of groups,
in the second crystallization treatment process, the temperature of the system is raised to 150-195 ℃ at a heating rate of 1-10 ℃/min; and/or the number of the groups of groups,
the second crystallization treatment time is 16-72 h.
8. A catalyst prepared by the preparation method according to any one of claims 1 to 7.
9. A process for producing propylene, comprising dehydrogenating propane with the catalyst according to claim 8 to obtain propylene.
10. The propylene production process according to claim 9, wherein the dehydrogenation treatment is performed using one or more fixed bed reactors having a heating function.
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CN116495736A (en) * 2023-06-13 2023-07-28 昆明理工大学 Method for preparing MXees composite material efficiently by flash freezing and microwaves

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JP2007302530A (en) * 2006-05-12 2007-11-22 Toyota Motor Corp Metal oxide particle and manufacturing method thereof as well as exhaust gas purifying catalyst
CN109502607A (en) * 2018-11-30 2019-03-22 中国科学院山西煤炭化学研究所 A kind of synthetic method of nanometer of ZSM-22 molecular sieve
CN113600230A (en) * 2021-08-02 2021-11-05 大连理工大学 Efficient monatomic molecular sieve forming catalyst and preparation method thereof
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