CN113042095A - Molecular sieve catalyst, preparation method and application thereof - Google Patents

Molecular sieve catalyst, preparation method and application thereof Download PDF

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CN113042095A
CN113042095A CN202110284781.1A CN202110284781A CN113042095A CN 113042095 A CN113042095 A CN 113042095A CN 202110284781 A CN202110284781 A CN 202110284781A CN 113042095 A CN113042095 A CN 113042095A
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molecular sieve
sieve catalyst
catalyst
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metal
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CN113042095B (en
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田亚杰
王涛
周帅帅
代磊
乔聪震
杨浩
段浩楠
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Henan University
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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
    • B01J29/04—Catalysts comprising molecular sieves having base-exchange properties, e.g. crystalline zeolites
    • B01J29/06—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof
    • B01J29/40—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof of the pentasil type, e.g. types ZSM-5, ZSM-8 or ZSM-11, as exemplified by patent documents US3702886, GB1334243 and US3709979, respectively
    • B01J29/42—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof of the pentasil type, e.g. types ZSM-5, ZSM-8 or ZSM-11, as exemplified by patent documents US3702886, GB1334243 and US3709979, respectively containing iron group metals, noble metals or copper
    • B01J29/46—Iron group metals or copper
    • 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
    • B01J35/00—Catalysts, in general, characterised by their form or physical properties
    • B01J35/30—Catalysts, in general, characterised by their form or physical properties characterised by their physical properties
    • B01J35/391—Physical properties of the active metal ingredient
    • B01J35/393—Metal or metal oxide crystallite size
    • 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
    • B01J35/00—Catalysts, in general, characterised by their form or physical properties
    • B01J35/60—Catalysts, in general, characterised by their form or physical properties characterised by their surface properties or porosity
    • B01J35/61—Surface area
    • 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
    • B01J35/00—Catalysts, in general, characterised by their form or physical properties
    • B01J35/60—Catalysts, in general, characterised by their form or physical properties characterised by their surface properties or porosity
    • B01J35/63—Pore volume
    • C—CHEMISTRY; METALLURGY
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    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C4/00—Preparation of hydrocarbons from hydrocarbons containing a larger number of carbon atoms
    • C07C4/02—Preparation of hydrocarbons from hydrocarbons containing a larger number of carbon atoms by cracking a single hydrocarbon or a mixture of individually defined hydrocarbons or a normally gaseous hydrocarbon fraction
    • C07C4/025—Oxidative cracking, autothermal cracking or cracking by partial combustion
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10G—CRACKING HYDROCARBON OILS; PRODUCTION OF LIQUID HYDROCARBON MIXTURES, e.g. BY DESTRUCTIVE HYDROGENATION, OLIGOMERISATION, POLYMERISATION; RECOVERY OF HYDROCARBON OILS FROM OIL-SHALE, OIL-SAND, OR GASES; REFINING MIXTURES MAINLY CONSISTING OF HYDROCARBONS; REFORMING OF NAPHTHA; MINERAL WAXES
    • C10G11/00—Catalytic cracking, in the absence of hydrogen, of hydrocarbon oils
    • C10G11/02—Catalytic cracking, in the absence of hydrogen, of hydrocarbon oils characterised by the catalyst used
    • C10G11/04—Oxides
    • C10G11/05—Crystalline alumino-silicates, e.g. molecular sieves

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Abstract

The invention provides a molecular sieve catalyst, a preparation method and application thereof. The molecular sieve catalyst comprises a molecular sieve support comprising agglomerates; the agglomerate comprises a lamellar structure, and a plurality of lamellar structures are stacked to enable the molecular sieve carrier to have a porous structure; and an active ingredient, wherein the active ingredient comprises a metal and/or a metal oxide, and the average particle size of the active ingredient is 0.5-10 nm; wherein at least 95% or more of the active ingredient, based on the total mass of the active ingredient, is encapsulated between at least two of the lamellar structures of the agglomerate. The molecular sieve catalyst of the invention has the following technical effects: the metal cluster thermal stability of the limited area in the layered molecular sieve micropore duct and between layers is obviously enhanced, and the dispersion degree is obviously improved.

Description

Molecular sieve catalyst, preparation method and application thereof
Technical Field
The invention relates to a molecular sieve catalyst, a preparation method and application thereof, in particular to a layered MFI structure molecular sieve catalyst with transition metal oxide nanoparticles or transition metal nanoparticles encapsulated between layers, a preparation method and application thereof, and belongs to the field of catalysts.
Background
The MFI type molecular sieve material is widely applied to reactions such as catalytic cracking, catalytic reforming and the like due to excellent hydrothermal stability, rich porous structure and adjustable acidity distribution, and the synthesis of the MFI molecular sieve (layered) with the 2-dimensional structure provides a new idea for solving the conversion of hydrocarbon molecules. Compared with the traditional molecular sieve, the layered MFI molecular sieve with the ultrashort b-axis (2 nm) has higher external surface area and mesopore volume, has an effective factor for macromolecular reaction close to 1, is far higher than a micron or even nanometer molecular sieve, and has higher absorption-desorption rate for hydrocarbon molecules. Researchers have shown higher catalytic activity in the reaction of catalyzing hydrocarbon cracking to prepare low-carbon olefin compared with the traditional molecular sieve by loading a metal-constructed bifunctional catalyst on the layered molecular sieve and combining rapid diffusion brought by the ultrashort b-axis/rich mesopores of the layered molecular sieve with the metal active site for concerted catalysis.
The catalyst is constructed by compounding the modified transition metal element and the layered MFI molecular sieve, and the cracking conversion rate and the yield of low-carbon olefin in the product are improved by utilizing the adsorption of metal clusters on reactant molecules and the modulation on the acidity of a carrier and combining the rapid diffusion characteristic of the layered molecular sieve. However, the metal/layered MFI molecular sieve prepared by the conventional impregnation method and the ion exchange method has the problems of low thermal stability (a two-dimensional structure and metal particles), difficult control of metal distribution and the like, and restricts the application of the metal/layered MFI molecular sieve in the preparation of low-carbon olefin by catalytic cracking. The main problems are as follows:
(1) the molecular sieve supported metal catalyst prepared by the traditional impregnation or ion exchange method is easy to agglomerate at high temperature due to Ostwald ripening and Brownian motion of transition metal particles, so that the metal catalysis effect is reduced, and the pores are plugged to deactivate the catalyst.
(2) The hydrophobic long chain in the double-amino template agent controls the growth of the lamella in the b-axis direction, but the roasting process in the preparation process enables the 'barrier' between layers to disappear, the Si-O-Si bond is formed again, and a large-size crystal is partially generated, so that the collapse of a 2-dimensional structure is caused, the ordered mesopores disappear, and the surface area is reduced.
(3) The cracking depth is increased due to the higher reaction temperature (>500 ℃) of the catalytic cracking reaction, the catalyst is inactivated due to the active metal and the acid center being covered by carbon deposition, and the catalytic stability is reduced. Along with the reaction, based on the structural characteristic of low layered thermal stability, the mesoporous and limited microporous orifices with low connectivity are covered by carbon deposition, and the diffusion process of the intermediate product is further deteriorated, so that the occurrence of secondary reaction is aggravated, and aromatic hydrocarbon is formed and further polymerized into the carbon deposition to inactivate the catalyst.
Disclosure of Invention
Problems to be solved by the invention
In view of the technical problems in the prior art, for example: the invention provides a molecular sieve catalyst, which has the problems of easy inactivation, few ordered mesopores, low surface area and the like.
Furthermore, the invention also provides a preparation method of the molecular sieve catalyst, which is simple and feasible, has easily obtained raw materials and is suitable for mass production.
Means for solving the problems
The invention first provides a molecular sieve catalyst, wherein the molecular sieve catalyst comprises:
a molecular sieve support comprising agglomerates; the agglomerate comprises a lamellar structure, and a plurality of lamellar structures are stacked to enable the molecular sieve carrier to have a porous structure; and
an active ingredient comprising a metal and/or a metal oxide, the active ingredient having an average particle diameter of 0.5 to 10 nm; wherein
At least 95% or more of the active ingredient, based on the total mass of the active ingredient, is encapsulated between at least two of the lamellar structures of the agglomerate.
The molecular sieve catalyst provided by the invention is characterized in that the content of the active component is 0.01-10% of the total mass of the molecular sieve catalyst; and/or
The metal element in the active component is one or the combination of more than two of iron, nickel and cobalt.
The molecular sieve catalyst provided by the invention is characterized in that the particle size of each aggregate is 0.5-10 mu m; and/or the thickness of the single lamellar structure is 1.4-4 nm.
The molecular sieve catalyst provided by the invention is characterized in that the molecular sieve carrier is of an MFI structure; and/or the surface area of the molecular sieve catalyst is 250-700m2Per g, pore volume of 0.3-0.8cm3/g。
The invention also provides a preparation method of the molecular sieve catalyst, which comprises the following steps:
preparing a precursor solution containing an active ingredient;
carrying out hydrothermal crystallization treatment on the precursor solution to obtain a hydrothermal crystallization product;
roasting the hydrothermal crystallization product to remove the template agent to obtain a catalyst precursor;
carrying out ion exchange on the catalyst precursor under the condition of having ammonium salt to obtain an ammonium catalyst precursor;
and roasting the ammonium catalyst precursor, and then reducing in a hydrogen atmosphere to obtain the molecular sieve catalyst.
The preparation method of the precursor solution comprises the following steps:
mixing a silicon source, an alkali source and an optional aluminum source in a solvent to obtain an alkaline mixed solution;
mixing a template agent, a metal salt, a complexing agent and an acid source in a solvent to obtain an acidic mixed solution;
and mixing the acidic mixed solution and the alkaline mixed solution to obtain a precursor solution.
The preparation method comprises the following steps of (1) preparing a template agent, wherein the template agent comprises a biquaternary ammonium salt template agent; preferably, the biquaternary ammonium salt template agent is CnH2n+1N+(CH3)2-(CH2)mN+(CH3)2-(CH2)kCH3·2Br-Wherein n is an integer of 10 to 30, m is an integer of 1 to 10, and k is an integer of 1 to 10.
The preparation method of the invention comprises the steps of adding an alkali source, an acid source and SiO in the precursor solution2Template agent, Al2O3The molar ratio of the active ingredient to the complexing agent to the solvent is (5-60): (2-30): 100: (2-20): (0-50): (1-10): (1-10): (2000-6000).
The preparation method comprises the following steps of (1) performing hydrothermal crystallization at 130-170 ℃ for 2-15 days;
the roasting is carried out in an oxygen-containing atmosphere and/or a hydrogen-containing atmosphere, the roasting temperature is 300-600 ℃, and the roasting time is 4-12 h;
the ion exchange temperature is 50-90 ℃, and the ion exchange time is 2-4 h;
the reduction temperature is 300-700 ℃, and the reduction time is 0.1-5 h.
The invention also provides an application of the molecular sieve catalyst or the molecular sieve catalyst prepared by the preparation method in catalyzing hydrocarbon cracking reaction to prepare low-carbon olefin.
ADVANTAGEOUS EFFECTS OF INVENTION
The molecular sieve catalyst of the invention has the following technical effects: the metal cluster thermal stability of the limited area in the layered molecular sieve micropore duct and between layers is obviously enhanced, and the dispersion degree is obviously improved. The active components of the invention obviously improve the stability of the layered MFI molecular sieve and obviously enhance the connectivity and the orderliness of the pore channels. The rapid diffusion channel and the high dispersion metal obviously enhance the carbon deposition resistance of the catalyst and obviously improve the catalytic stability.
Furthermore, the preparation method is simple and feasible, the raw materials are easy to obtain, and the metal particles can be uniform in size, uniform in dispersion and certain in lattice regularity, so that the preparation method is suitable for mass production.
Furthermore, the molecular sieve catalyst can be used for catalyzing hydrocarbon cracking reaction to prepare low-carbon olefin.
Drawings
FIG. 1 is an SEM image of a sample of the molecular sieve catalyst prepared in example 1;
FIG. 2 is an SEM image of a sample of the molecular sieve catalyst prepared in example 2;
FIGS. 3A and 3B are XRD patterns of samples of molecular sieve catalysts prepared in examples 1 and 2, respectively;
FIG. 4 is a TEM image of a sample of the molecular sieve catalyst prepared in example 4;
FIG. 5 is an XPS plot of the Ni2p orbital of a sample of the molecular sieve catalyst prepared in example 1;
FIG. 6 is an SEM image of a sample of the molecular sieve catalyst prepared in example 6;
FIG. 7 is an SEM image of a sample of the molecular sieve catalyst prepared in example 7;
FIGS. 8A and 8B are XRD patterns of samples of molecular sieve catalysts prepared in examples 6 and 7, respectively;
FIG. 9 is a TEM image of a sample of the molecular sieve catalyst prepared in example 9;
FIG. 10 is an SEM image of a sample of the molecular sieve catalyst prepared in example 11;
FIG. 11 is an SEM image of a sample of the molecular sieve catalyst prepared in example 12;
FIGS. 12A and 12B are XRD patterns of samples of molecular sieve catalysts prepared in examples 11 and 12, respectively;
FIG. 13 is a TEM image of a sample of the molecular sieve catalyst prepared in example 14;
FIG. 14 is an SEM image of a sample of the molecular sieve catalyst prepared in example 16;
FIG. 15 is an SEM image of a sample of the molecular sieve catalyst prepared in example 17;
FIG. 16 is a TEM image of a sample of the molecular sieve catalyst prepared in example 18;
FIG. 17 is a graph of the catalytic cracking conversion activity for n-heptane for the molecular sieve catalyst prepared in example 6;
FIG. 18 is a graph of the yield of propylene from n-heptane catalyzed cleavage product for the molecular sieve catalyst prepared in example 6.
Detailed Description
The present invention will be described in detail below. The technical features described below are explained based on typical embodiments and specific examples of the present invention, but the present invention is not limited to these embodiments and specific examples. It should be noted that:
in the present specification, the numerical range represented by "numerical value a to numerical value B" means a range including the end point numerical value A, B.
In the present specification, "plural" in "plural", and the like means a numerical value of 2 or more unless otherwise specified.
In the present specification, "%" denotes mass% unless otherwise specified.
In the present specification, the meaning of "may" includes both the meaning of performing a certain process and the meaning of not performing a certain process.
In this specification, "optional" or "optionally" means that the subsequently described event or circumstance may or may not occur, and that the description includes instances where the event occurs and instances where it does not.
In the present specification, reference to "some particular/preferred embodiments," "other particular/preferred embodiments," "embodiments," and the like, means that a particular element (e.g., feature, structure, property, and/or characteristic) described in connection with the embodiment is included in at least one embodiment described herein, and may or may not be present in other embodiments. In addition, it is to be understood that the described elements may be combined in any suitable manner in the various embodiments.
The temperature referred to herein as "room temperature" is generally between "10-40 ℃.
First aspect
A first aspect of the invention provides a molecular sieve catalyst comprising:
a molecular sieve support comprising agglomerates; the agglomerate comprises a lamellar structure, and a plurality of lamellar structures are stacked to enable the molecular sieve carrier to have a porous structure; and
an active ingredient comprising a metal and/or a metal oxide, the active ingredient having an average particle diameter of 0.5 to 10 nm; wherein
At least 95% or more of the active ingredient, based on the total mass of the active ingredient, is encapsulated between at least two of the lamellar structures of the agglomerate.
Further, in the invention, the surface area of the molecular sieve catalyst is 250-700m2Per g, pore volume of 0.3-0.8cm3(ii) in terms of/g. The molecular sieve catalyst has high surface area and pore volume, and is excellent in performance.
The molecular sieve catalyst provided by the invention effectively improves the mass transfer diffusion rate of hydrocarbon molecules by utilizing the hierarchical pores constructed by the ultrashort b-axis (micropore) and interlayer mesopores of the molecular sieve carrier with a specific structure, thereby improving the catalytic cracking reaction rate; and the transition metal dispersed among the layers can effectively regulate and control the acidity strength and acid distribution of the carrier, and the characteristics of the transition metal suitable for surface acidity and highly ordered dispersion of metal particles enable the transition metal to become a catalytic material with excellent performance in the aspect of catalytic cracking.
The rapid diffusion channel and the high dispersion metal of the molecular sieve catalyst obviously enhance the carbon deposition resistance of the catalyst and obviously improve the catalytic stability. The layered molecular sieve packaging metal type catalyst constructed by the invention has the acid active center (activating C-H and C-C bonds) and the metal active center (promoting molecular adsorption and regulating the B/L ratio of the molecular sieve) of the molecular sieve, and improves the accessibility of the active centers by utilizing the lamellar ultrashort B axis and the interlayer ordered mesopores, thereby improving the conversion rate of reactants; on the other hand, the rapid diffusion channel can remarkably reduce the cracking reaction depth, inhibit secondary reactions including hydrogen transfer, cyclization, polymerization and the like, improve the yield of low-carbon olefin and reduce the generation of carbon deposition precursors; meanwhile, the high specific surface constructed by the column support can effectively improve the carbon capacity of the catalyst and improve the catalytic stability in many aspects.
Molecular sieve carrier
The catalytic cracking of hydrocarbon raw material is developed on the basis of steam cracking, and can obviously reduce cracking reaction temperature (<The yield of propylene is increased while the temperature is 600 ℃; and the existing equipment can be used for simple upgrading and reconstruction, the equipment investment is reduced, and the selection range of cracking raw materials is widened, so that the method is widely concerned by researchers. Among various cracking catalysts, the MFI type molecular sieve composed of aluminosilicate framework has rich active sites and good shape selectivity, and reactants pass through a straight type
Figure BDA0002979991670000061
And sine
Figure BDA0002979991670000062
The pore channel is cracked at the surface acid site to generate low-carbon olefin micromolecule compounds including ethylene, propylene and the like, and meanwhile, the generation of macromolecular aromatic hydrocarbon products can be effectively inhibited, so that the catalyst is the most ideal catalytic material at present.
The synthesis of the two-dimensional structure molecular sieve (lamellar) provides a new idea for solving the problem of hydrocarbon molecule conversion. Compared with the traditional molecular sieve, the layered MFI molecular sieve with the ultrashort b-axis (2 nm) has higher external surface area and mesopore volume, has an effective factor for macromolecular reaction close to 1, is far higher than a micron or even nanometer molecular sieve, and has higher absorption-desorption rate for hydrocarbon molecules. The metal-loaded double-function catalyst is constructed by loading metal on the layered molecular sieve, and the rapid diffusion brought by the ultrashort b-axis/rich mesopores of the layered molecular sieve and the metal active site are combined for concerted catalysis. In general, in the ultra-thin layer MFI, a rapid diffusion channel and a high surface area are constructed by (010) oriented crystal planes, and meanwhile, the cracking conversion rate of n-heptane, the propylene selectivity and the carbon deposition resistance are improved.
In the present invention, the molecular sieve support comprises agglomerates; the agglomerate comprises a lamellar structure, and a plurality of lamellar structures are stacked mutually so that the molecular sieve carrier has a porous structure. Specifically, the molecular sieve carrier disclosed by the invention is of an MFI structure. The molecular sieve catalyst disclosed by the invention effectively improves the molecular mass transfer diffusion rate by utilizing a lamella ultrashort b-axis structure and an interlayer MFI structure ordered mesoporous structure; the modification and modulation of the acid center on the surface of the molecular sieve are combined with the high-dispersion metal, so that the reaction rate of the catalytic reaction and the yield of the low-carbon olefin in the product are improved; and the characteristics of multiple active sites and highly ordered dispersion of metal particles make the catalyst material become a catalytic material with excellent performance in the field of preparing low-carbon olefins by catalytic cracking.
In some specific embodiments, the thickness of the single lamellar structure is 1.4 to 4 nm. Due to the existence of a large number of lamellar structures at the thickness, the molecular sieve carrier with a porous structure can be formed by the method.
Active ingredient
The active ingredient of the invention contains metal and/or metal oxide, and the invention can reduce the surface acid strength of the molecular sieve carrier by utilizing the modification of the active ingredient, inhibit the cracking depth and further improve the selectivity of the intermediate product, namely the low-carbon olefin. For example, the transition metal elements (Fe, Co, Ni) can be bonded with the surface of the molecular sieve through bridge type hydroxyl
Figure BDA0002979991670000071
The acid is converted into Lewis acid, so that the hydrogen transfer reaction degree is restrained, and meanwhile, the proper amount of 'alkalinity' brought by the Lewis acid can promote the desorption of olefin molecules on acid sites, restrain the bimolecular polymerization reaction of low-carbon olefin, and improve the hydrocarbon cracking conversion rate and the low-carbon olefin yield. In fact, the active centers of the present invention are molecular sieve surface acidity, metals and/or metal oxides. Wherein the acid center comprises
Figure BDA0002979991670000072
Acids and Lewis acids.
Further, the average particle size of the active ingredient is 0.5 to 10 nm. Most of the active ingredients of the invention can be encapsulated between the layers of the molecular sieve carrier with a layered MFI structure, and can realize uniform dispersion and form a highly ordered distribution state, and meanwhile, the multi-stage pore channel structure of the molecular sieve limits the high-temperature aggregation of the active ingredients, thereby further improving the activity and selectivity of the active ingredients in the catalytic reaction. In the present invention, at least 95% or more of the active ingredient, based on the total mass of the active ingredient, is encapsulated between at least two of the lamellar structures of the agglomerate.
In some specific embodiments, the active ingredient is present in an amount of 0.01 to 10% by mass based on the total mass of the molecular sieve catalyst, for example, the active ingredient may be added in an amount of 0.1%, 0.4%, 0.8%, 1%, 1.5%, 2%, 3%, 4%, 6%, 8%, 10%, etc.
Further, in the present invention, the metal element of the active ingredient of the present invention is not particularly limited, and may be some transition metal elements commonly used in the art. Specifically, in the present invention, one or a combination of two or more of transition metal elements such as iron, cobalt, nickel, and the like, which are widely available and low in cost, may be selected as the active ingredient. As for the source of the active ingredient, it may be derived specifically from metal salts and the like.
The active ingredient of the present invention may be referred to as an "interlayer metal pillar". The interlayer metal column support structure obviously improves the stability of the layered MFI molecular sieve and obviously enhances the connectivity and the orderliness of the pore channel. The ordered arrangement of the mesopores among the lamella layers is kept through interlayer column support, so that the layered structure can be inhibited from being converted from two-dimensional to three-dimensional under the high-temperature roasting. The interlayer metal pillared structure constructed by the method can greatly retain ordered mesopores among the sheet layers, improve the surface area and promote the diffusion of reactants and products; meanwhile, ordered mesopores among layers can be kept by utilizing the pillaring effect of the metal oxide in situ, and the existing ultrashort b-axis diffusion path of the layered molecular sieve is combined to obtain the molecular sieve catalyst with the rapid diffusion characteristic.
Second aspect of the invention
A second aspect of the invention provides a process for the preparation of a molecular sieve catalyst according to the first aspect of the invention, comprising the steps of:
preparing a precursor solution containing an active ingredient;
carrying out hydrothermal crystallization treatment on the precursor solution to obtain a hydrothermal crystallization product;
roasting the hydrothermal crystallization product to remove the template agent to obtain a catalyst precursor;
carrying out ion exchange on the catalyst precursor under the condition of having ammonium salt to obtain an ammonium catalyst precursor;
and roasting the ammonium catalyst precursor, and then reducing in a hydrogen atmosphere to obtain the molecular sieve catalyst.
The preparation method of the invention can limit the active ingredients in the micropore channels and between the lamellar structures of the molecular sieve catalyst. And the thermal stability of the metal cluster containing the active ingredient is obviously enhanced, and the dispersity is obviously improved.
Precursor solution
In the invention, the preparation method of the precursor solution comprises the following steps:
mixing a silicon source, an alkali source and an optional aluminum source in a solvent to obtain an alkaline mixed solution;
mixing a template agent, an active ingredient, a complexing agent and an acid source in a solvent to obtain an acidic mixed solution;
and mixing the acidic mixed solution and the alkaline mixed solution to obtain a precursor solution.
Specifically, in some specific embodiments of the present invention, as the silicon source, silica gel, fumed silica, inorganic silicate, organosilicate, silica or silicic acid or any mixture thereof may be used.
As for the aluminum source of the present invention, it may be one or more of an organoaluminum compound, pseudoboehmite, aluminum gel, and an organic acid salt, inorganic acid salt or a complex thereof and a hydrate containing aluminum. Preferably, the aluminium source of the present invention may be selected from pseudo-boehmite, alumina, aluminium gel, sodium aluminate, aluminium phosphate, aluminium chloride, aluminium sulphate, aluminium nitrate, aluminium isopropoxide or aluminium hydroxide or any mixture thereof. In some specific embodiments, the aluminum source comprises NaAlO2、Al(NO3)3、Al2(SO4)3、AlCl3Or Al (OCH (CH)3)2)3One or a combination of two or more of them.
In the present invention, the optional alkali source may be any available alkaline material in the art, and in some specific embodiments, the alkali source comprises sodium hydroxide or potassium hydroxide.
In the present invention, the templating agent also plays an important role. In general, crystalline materials in either the amorphous or dense phase may be obtained in the absence of a templating agent. The template agent has the main function of structure guiding, different template agents are adopted to have obvious influence on the formed framework structure and the product property, and meanwhile, the template agent can also control the distribution of silicon on the framework. As for the template agent usable in the present invention, it may include a biquaternary ammonium salt template agent in which an ammonium group is selectively induced to form a molecular sieve skeleton, and a long carbon chain portion forms a barrier between the molecular sieve skeletons by utilizing its hydrophobic property to inhibit its growth in a certain direction to form a sheet-like structure. Preferably, the biquaternary ammonium salt template agent can be CnH2n+1N+(CH3)2-(CH2)mN+(CH3)2-(CH2)kCH3·2Br-Wherein n is an integer of 10 to 30, m is an integer of 1 to 10, and k is an integer of 1 to 10. In some specific embodiments, the templating agent can be C22H45N+(CH3)2-(CH2)6N+(CH3)2-(CH2)6CH3·2Br-，C18H37N+(CH3)2-(CH2)4N+(CH3)2-(CH2)6CH3·2Br-，C16H33N+(CH3)2-(CH2)4N+(CH3)2-(CH2)6CH3·2Br-And a combination of one or both of them.
For the metal salt, the metal salt may be one or a combination of two or more of iron salt, cobalt salt, and nickel salt. Specifically, the iron salt comprises one or a combination of more than two of ferric nitrate, ferric chloride, ferric sulfate, ferrous nitrate, ferrous chloride and ferrous sulfate; the cobalt salt comprises one or the combination of more than two of cobalt sulfate, cobalt nitrate and cobalt chloride; the nickel salt comprises one or the combination of more than two of nickel nitrate, nickel chloride and nickel sulfate.
The invention induces metal to distribute among the lamellar structures of the molecular sieve catalyst by using a complexing agent. The complexing agent may have silane groups and ammonium groups, which are the more critical factors for inducing metal distribution between the layers of the layered molecular sieve. The application adopts an in-situ synthesis method, and introduces a complexing agent into a precursor solution for complexing metal. Wherein, the ammonium group keeps the stable existence of the metal precursor under the alkaline condition, the silane group participates in the nucleation of the molecular sieve to induce the metal to be fixed on the surface of the molecular sieve, and the metal particles are introduced into micropores of the layered molecular sieve and between the layered layers under the hydrothermal condition. The metal-loaded cracking catalyst with high diffusion property, high metal thermal stability and dispersity is constructed in situ, and the yield of low-carbon olefin in the cracking reaction can be improved. And the metal or metal oxide is converted into metal or metal oxide through a subsequent roasting process to form a micropore confinement and a layered interlayer confinement respectively, so that the metal-loaded molecular sieve catalyst with high dispersion and high thermal stability is prepared.
Specifically, in the present invention, the complexing agent is N- [3- (trimethoxysilyl) propyl ] ethylenediamine, N- [3- (trimethoxysilyl) butyl ] ethylenediamine, etc., so that a silane group can be formed to complex a metal structure, which is written as: M-NMP, wherein M can be Fe, Co and Ni).
As the solvent, the present invention is not particularly limited, and may be any solvent that can be used in the art, for example: polar solvents such as water or alcohols. Water is preferably used as the solvent.
Further, in the precursor solution, an alkali source, an acid source and SiO2Template agent, Al2O3The molar ratio of the active ingredient to the complexing agent to the solvent is (5-60): (2-30): 100: (2-20): (0-50): (1-10): (1-10): (2000-6000).
Further, the mixing method of the acidic mixed solution and the alkaline mixed solution is not particularly limited in the present invention. Generally, the mixing may be performed at normal temperature, and specifically, the mixture may be stirred at room temperature for 24-48 hours, so as to obtain a crystallization liquid, i.e., a precursor solution. The solvent used in the present invention is not particularly limited, and may be any polar solvent commonly used in the art, for example: water, and the like.
Step of hydrothermal crystallization
And carrying out hydrothermal crystallization treatment on the precursor solution to obtain a hydrothermal crystallization product. Specifically, the obtained precursor solution is placed in a hydrothermal reaction kettle for hydrothermal crystallization treatment to obtain a hydrothermal crystallization product. For example, a stainless steel hydrothermal reaction kettle containing a teflon liner may be used.
The temperature for the hydrothermal crystallization treatment may be 120 ℃ or higher and 180 ℃ or lower, and preferably may be 130 to 170 ℃; the hydrothermal crystallization treatment may be carried out for 2 to 25 days, preferably for 4 to 13 days.
Furthermore, the invention generally carries out post-treatment operations such as washing, drying and the like on the hydrothermal crystallization product. Specifically, for washing, water can be used for washing to be neutral, the drying can be carried out at the temperature of 80-140 ℃, and the drying time can be 8-16 h.
Roasting
And (3) roasting the hydrothermal crystallization product for one time to remove the template agent, thereby obtaining the catalyst precursor. The conditions for the primary calcination are not particularly limited, and may be: calcining for 4 to 12 hours at the temperature of between 300 and 600 ℃.
Further, the primary calcination is performed in an oxygen-containing atmosphere and/or a hydrogen-containing atmosphere. Preferably, the reaction may be carried out in an oxygen-containing atmosphere and then in a hydrogen-containing atmosphere. As the oxygen-containing atmosphere, an air atmosphere or the like may be mentioned.
Ion exchange
In the present invention, the ion exchange step mainly utilizes NH in the molecular sieve4 +With Na+The exchange function of (2) is realized. Specifically, after primary calcination, the catalyst precursor is subjected to an ion exchange treatment with an ammonium salt to obtain an ammonium-type catalyst precursor.
Ion exchange, namely changing cations for balancing the charges of the molecular sieve framework into ammonium ions through ion exchange, and then converting the ammonium ions into a hydroxyl structure through high-temperature treatment, wherein the hydroxyl on the surface of the molecular sieve can act synergistically with the packaging metal to provide an acid site for related catalytic reaction. Specifically, the ion exchange treatment may be performed in an ammonium salt solution, and the ammonium salt solution is not particularly limited in the present invention, and may be an ammonium salt solution commonly used in the art, for example: ammonium chloride or ammonium nitrate, and the like. For the conditions of the ion exchange treatment, the temperature of the ammonium exchange treatment is 50-90 ℃, and the time of the ammonium exchange treatment is 2-4 h.
Post-treatment
After the ion exchange treatment, the second baking may be performed. The conditions for the secondary calcination are not particularly limited, and may be the same as those for the primary calcination, specifically, calcination at a temperature of 300 to 600 ℃ for 4 to 12 hours. The secondary roasting is carried out in oxygen-containing atmosphere and/or hydrogen-containing atmosphere. Preferably, the reaction may be carried out in an oxygen-containing atmosphere and then in a hydrogen-containing atmosphere. As the oxygen-containing atmosphere, an air atmosphere or the like may be mentioned.
Further, roasting the ammonium catalyst precursor, and then reducing in a hydrogen atmosphere to obtain the molecular sieve catalyst.
In addition, the molecular sieve catalyst containing metal oxide can be reduced under hydrogen atmosphere, so that the molecular sieve catalyst of the invention can be obtained; wherein the reduction temperature is 300-700 ℃, and the reduction time can be 0.1-5 h.
The preparation method of the invention is characterized in that a transition metal complex with a specific structure is introduced into a molecular sieve precursor solution, and a lamellar MFI structure molecular sieve is synthesized by a hydrothermal crystallization method. The transition metal is introduced into the lamellar molecular sieve by the cooperation of a metal complex with a specific structure, nano metal particles are converted into metal oxide and encapsulated between lamellar molecular sieve layers while a template agent is removed by baking, and finally the metal is reduced from a fixed position in a hydrogen atmosphere. The preparation method can avoid the aggregation of metal nano particles, so that the metal particles are uniformly dispersed and present certain lattice regularity, and the encapsulated metal and/or metal oxide catalyst among the layers of the layered MFI molecular sieve is obtained.
Third aspect of the invention
The third aspect of the present invention provides a use of the molecular sieve catalyst according to the first aspect of the present invention or the molecular sieve catalyst prepared by the preparation method according to the second aspect of the present invention in a reaction for preparing light olefins by catalytic cracking of hydrocarbons. Specifically, the molecular sieve catalyst with the layered MFI structure and the encapsulated active ingredients can be used for catalyzing the cracking reaction of organic compounds such as n-heptane and the like to prepare low-carbon olefin.
Examples
Embodiments of the present invention will be described in detail below with reference to examples, but those skilled in the art will appreciate that the following examples are only illustrative of the present invention and should not be construed as limiting the scope of the present invention. The examples, in which specific conditions are not specified, were conducted under conventional conditions or conditions recommended by the manufacturer. The reagents or instruments used are not indicated by the manufacturer, and are all conventional products commercially available.
The template agent used in the invention is exemplified by propane (TPAOH), the silicon source used is exemplified by Tetraethoxysilane (TEOS), and the aluminum source used is exemplified by aluminum sulfate (Al)2(SO4)3·18H2O) is taken as an example, the used water is deionized water, and the used reagents are all analytical pure reagents; the high power transmission microscope test of the obtained finished product is carried out by using JEM-2100, the accelerating voltage is 200KV, the content of metal in the obtained finished product is determined by an element analyzer ICP-9000(N + M), and the X-ray diffraction analysis test of the obtained finished product is determined by a Bruker D8-Focus X-ray diffractometer.
[ examples 1 to 5 ]
Taking certain mass of aluminum sulfate (Al)2(SO4)3·18H2O, a source of silicon of a certain mass, 0.7g of sodium hydroxide (NaOH), and 13.707g H2Preparing alkaline mixed liquor by using O; 0.4235g concentrated sulfuric acid (H)2SO4,>98 percent of nickel nitrate (Ni (NO)) with a certain mass3)2·6H2O), 2.116g of a bis-quaternary ammonium salt template (C)22H45N+(CH3)2-(CH2)6N+(CH3)2-(CH2)6CH3·2Br-) 0.2436gN- [3- (trimethoxysilyl) propyl group]Preparing an acidic mixed solution from ethylenediamine (NMP) and 17.8145g of deionized water, stirring the prepared acidic mixed solution and an alkaline mixed solution at room temperature for 24 hours to obtain a crystallization solution, placing the crystallization solution in a crystallization kettle, and carrying out hydrothermal crystallization at 140 ℃ for 10 days to obtain a hydrothermal crystallization product; washing the synthesized hydrothermal crystallization product powder with deionized water to be neutral, drying for 12h at 100 ℃, and roasting for 6h at 500 ℃ in air atmosphere to obtain the layered MFI structure molecular sieve containing Ni oxide nanoparticlesAgent agglomerates (i.e., molecular sieve catalyst precursors).
Weighing 1g of calcined MFI structure molecular sieve catalyst containing Ni oxide nanoparticles, and adding 100mL of 1mol/L NH4Stirring the solution in Cl solution at 85 ℃ for 3h for ion exchange treatment, washing the solution with deionized water after the ion exchange treatment is finished, drying the solution at 100 ℃ for 24h, roasting the solution at 550 ℃ for 4h, and repeating the process for 3 times; then roasting for 6 hours in the air atmosphere at the temperature of 550 ℃; and then reducing the mixture for 2 hours at a constant temperature of 500 ℃ in a hydrogen atmosphere to obtain the layered MFI structure molecular sieve catalyst for encapsulating the Ni nano-particles.
Al used in example 12(SO4)3·18H2O was 0.1493g in mass, Tetraethylorthosilicate (TEOS) was 6.0763g in mass, and Ni (NO) was used3)2·6H2The O mass was 0.0862 g.
Al used in example 22(SO4)3·18H2The mass of O is 0.2986 g; the silica Sol (SiO) used250% aqueous solution) was 3.5g, and Ni (NO) was used3)2·6H2O mass 0.1724 g.
Al (NO) used in example 33)3Fumed Silica (SiO) used with a mass of 0.2188g2) Mass 1.75g, Ni (NO) used3)2·6H2O mass 0.3448 g.
AlCl used in example 430.0776g in mass, 6.0763g in mass of tetraethyl orthosilicate (TEOS), and Ni (NO) used3)2·6H2O mass 0.0431 g.
Al (NO) used in example 53)3Silica Sol (SiO) having a mass of 0.1269g was used250% aqueous solution) was 3.5g, and Ni (NO) was used3)2·6H2The mass of O is 0.0287 g.
An SEM image of the molecular sieve catalyst prepared in example 1 is shown in FIG. 1, and the obvious lamellar arrangement phenomenon of the powder sieve can be seen, and the lamellar stacking particle size is 7.1 μm;
an SEM image of the molecular sieve catalyst prepared in example 2 is shown in FIG. 2, and the obvious lamellar arrangement phenomenon of the powder sieve can be seen, and the lamellar stacking particle size is 3.6 μm;
the XRD patterns of the molecular sieve catalysts prepared in example 1 and example 2 are shown in fig. 3A and 3B, and the comparison of 44-0003 according to standard XRD (Jade 6) PDF cards shows that the prepared molecular sieve catalysts are all typical MFI crystal phases, and the changes of the aluminum content and the nickel content in the precursor solution do not affect the crystal forms.
A TEM image of the molecular sieve catalyst prepared in example 4 is shown in fig. 4, and it can be seen that the Ni oxide is highly uniformly dispersed among the lamellae of the molecular sieve catalyst, and the average particle size of the metal oxide obtained by statistics is 4.98 nm; the molecular sieve catalyst has a surface area of 327m2Per g, pore volume 0.467cm3/g。
An XPS chart corresponding to the Ni2p orbital of the molecular sieve catalyst prepared in example 1 is shown in fig. 5, and since the XPS test itself is a surface test means, it can be seen that when metal Ni exists between nanosheet layers, the peak intensity of the XPS spectrum corresponding to the Ni2p orbital is significantly lower than that of the molecular sieve catalyst directly supported;
the preparation method of the direct loading type contrast catalyst comprises the following steps: 0.1493g (Al)2(SO4)3·18H2O, 6.0763g of Tetraethylorthosilicate (TEOS), 0.7g of sodium hydroxide (NaOH), and 13.707g H g2Preparing alkaline mixed liquor by using O; 0.4235g concentrated sulfuric acid (H)2SO4，>98 percent), 2.116g of biquaternary ammonium salt template agent (C)22H45N+(CH3)2-(CH2)6N+(CH3)2-(CH2)6CH3·2Br-) Mixing the acid mixed solution with 17.8145g of deionized water to obtain an acid mixed solution, stirring the prepared acid mixed solution and an alkaline mixed solution at room temperature for 24 hours to obtain a crystallization solution, placing the crystallization solution in a crystallization kettle, and carrying out hydrothermal crystallization at 140 ℃ for 5 days to obtain a hydrothermal crystallization product; washing the synthesized hydrothermal crystallization product powder with deionized water to neutrality, drying at 100 ℃ for 12h, and roasting at 500 ℃ in air atmosphere for 6h to obtain the layered MFI junctionA molecular sieve carrier.
Weighing 1g of calcined layered MFI structure molecular sieve catalyst, and adding 100mL of 1mol/L NH4Stirring the solution in Cl solution at 85 ℃ for 3h for ion exchange treatment, washing the solution with deionized water after the ion exchange treatment is finished, drying the solution at 100 ℃ for 24h, roasting the solution at 550 ℃ for 4h, and repeating the process for 3 times; then roasting for 6 hours in the air atmosphere at 550 ℃; and then reducing the mixture for 2 hours at a constant temperature of 500 ℃ in a hydrogen atmosphere to prepare the H-type layered MFI structure molecular sieve catalyst (i.e. molecular sieve catalyst precursor).
0.0862 Nickel nitrate (Ni (NO) was weighed3)2·6H2O) is dissolved in 2mL of water to prepare a solution, 1g of prepared H-shaped sheet layered MFI structure molecular sieve is weighed as a carrier, metal Ni is dispersed on the outer surface of a layered molecular sieve cluster by adopting an isometric impregnation method, the drying is carried out for 12H at the temperature of 100 ℃, the roasting is carried out for 6H at the temperature of 500 ℃ in the air atmosphere, and then the constant temperature reduction is carried out for 2H at the temperature of 500 ℃ in the hydrogen atmosphere, so that the layered MFI structure molecular sieve catalyst with Ni nano particles loaded on the outer surface is prepared.
[ examples 6 to 10 ] to provide a toner
0.1493g (Al) was taken2(SO4)3·18H2O, 6.0763g of Tetraethylorthosilicate (TEOS), 0.7g of sodium hydroxide (NaOH), and 13.707g H g2Preparing alkaline mixed liquor by using O; 0.4235g concentrated sulfuric acid (H)2SO4，>98 percent), certain mass of ferric salt, 2.116g of biquaternary ammonium salt template agent (C)22H45N+(CH3)2-(CH2)6N+(CH3)2-(CH2)6CH3·2Br-) A certain mass of N- [3- (trimethoxysilyl) propyl group]Preparing an acidic mixed solution from ethylenediamine (NMP) and 17.8145g of deionized water, stirring the prepared acidic mixed solution and an alkaline mixed solution at room temperature for 24 hours to obtain a crystallization solution, placing the crystallization solution in a crystallization kettle, and carrying out hydrothermal crystallization at 140 ℃ for a certain time to obtain a hydrothermal crystallization product; washing the synthesized hydrothermal crystallization product powder with deionized water to neutrality, drying at 100 deg.C for 12h, and calcining at 500 deg.C in air atmosphere for 6h to obtain Fe-containing oxide nanoparticlesLayered MFI structure molecular sieve catalyst agglomerates (i.e., molecular sieve catalyst precursors) of particles.
Weighing 1g of calcined MFI structure molecular sieve catalyst containing Fe oxide nanoparticles, and adding 100mL of 1mol/L NH4Stirring the solution in Cl solution at 85 ℃ for 3h for ion exchange treatment, washing the solution with deionized water after the ion exchange treatment is finished, drying the solution at 100 ℃ for 24h, roasting the solution at 550 ℃ for 4h, and repeating the process for 3 times; then roasting for 6 hours in the air atmosphere at the temperature of 550 ℃; and then reducing the mixture for 2 hours at a constant temperature of 500 ℃ in a hydrogen atmosphere to obtain the layered MFI structure molecular sieve catalyst for encapsulating the Fe nano particles.
The iron salt used in example 6 was iron nitrate (Fe (NO)3·6H2O) has a mass of 0.0845 g; n- [3- (trimethoxysilyl) propyl radical used]The mass of ethylenediamine (NMP) was 0.2436 g; the hydrothermal crystallization time was 5 days.
The iron salt used in example 7 was iron nitrate (Fe (NO)3·6H2O) has a mass of 0.1136 g; n- [3- (trimethoxysilyl) propyl radical used]The mass of ethylenediamine (NMP) was 0.3654 g; the hydrothermal crystallization time was 6 days.
The iron salt used in example 8 was ferric chloride (FeCl)3·6H2O) has a mass of 0.1042 g; n- [3- (trimethoxysilyl) propyl radical used]The mass of ethylenediamine (NMP) was 0.1216 g; the hydrothermal crystallization time was 7 days.
The iron salt used in example 9 was ferrous chloride (FeCl)2·4H2O) has a mass of 0.1096 g; n- [3- (trimethoxysilyl) propyl radical used]The mass of ethylenediamine (NMP) was 0.2478 g; the hydrothermal crystallization time is 8 days.
The iron salt used in example 10 was iron nitrate (Fe (NO)3·6H2O) has a mass of 0.0845 g; n- [3- (trimethoxysilyl) propyl radical used]The mass of ethylenediamine (NMP) was 0.1218 g; the hydrothermal crystallization time is 10 days.
An SEM image of the molecular sieve catalyst prepared in example 6 is shown in FIG. 6, and the obvious lamellar arrangement of the powder sieve can be seen, and the lamellar stacking particle size is 7.1 μm;
an SEM image of the molecular sieve catalyst prepared in example 7 is shown in FIG. 7, and the obvious lamellar arrangement of the powder sieve can be seen, and the lamellar stacking particle size is 3.6 μm;
XRD of the molecular sieve catalysts prepared in the examples 6 and 7 is shown in figures 8A and 8B, and the comparison of 44-0003 of PDF card of standard XRD (Jade 6) shows that the prepared molecular sieve catalysts are typical MFI crystal phases, and the iron content in the precursor solution and the hydrothermal crystallization time change do not influence the crystal forms.
A TEM image of the molecular sieve catalyst prepared in example 9 is shown in fig. 9, which shows that iron oxide is highly uniformly dispersed among the lamellar structures of the molecular sieve catalyst, and the average particle size of the metal oxide obtained by statistics is 4.32 nm; the molecular sieve catalyst has a surface area of 463m2Per g, pore volume 0.554cm3/g。
[ examples 11 to 15 ]
0.0746g (Al) was taken2(SO4)3·18H2O, 6.0763g of Tetraethylorthosilicate (TEOS), 0.98g of sodium hydroxide (KOH), and 13.707g H2Preparing alkaline mixed liquor by using O; 0.4235g concentrated sulfuric acid (H)2SO4，>98 percent), cobalt salt with certain mass, 2.116g biquaternary ammonium salt template agent, 0.2436g N- [3- (trimethoxysilyl) propyl]Preparing an acidic mixed solution from ethylenediamine (NMP) and 17.8145g of deionized water, stirring the prepared acidic mixed solution and an alkaline mixed solution at room temperature for 24 hours to obtain a crystallization solution, placing the crystallization solution in a crystallization kettle, and carrying out hydrothermal crystallization at a certain temperature for 8 days to obtain a hydrothermal crystallization product; washing the synthesized hydrothermal crystallization product powder with deionized water to be neutral, drying for 12h at 100 ℃, and roasting for 6h at 500 ℃ in air atmosphere to obtain the layered MFI structure molecular sieve catalyst aggregate (i.e. molecular sieve catalyst precursor) containing the Co oxide nanoparticles.
Weighing 1g of calcined MFI structure molecular sieve catalyst containing Co oxide nanoparticles, and adding 100mL of 1mol/L NH4Stirring the solution in Cl solution at 85 ℃ for 3h for ion exchange treatment, washing the solution with deionized water after the ion exchange treatment is finished, drying the solution at 100 ℃ for 24h, roasting the solution at 550 ℃ for 4h, and repeating the process for 3 times; then roasting for 6 hours in the air atmosphere at the temperature of 550 ℃; then under hydrogenReducing for 2h at the constant temperature of 500 ℃ in the gas atmosphere to obtain the layered MFI structure molecular sieve catalyst for encapsulating the Co nanoparticles.
The cobalt salt used in example 11 was cobalt nitrate (Co (NO)3)2·6H2O) has a mass of 0.1297 g; the biquaternary ammonium salt template agent is C22H45N+(CH3)2-(CH2)6N+(CH3)2-(CH2)6CH3·2Br-(ii) a The hydrothermal crystallization time temperature is 150 ℃.
The cobalt salt used in example 12 was cobalt chloride (CoCl)2·6H2O) has a mass of 0.1061 g; the biquaternary ammonium salt template agent is C18H37N+(CH3)2-(CH2)4N+(CH3)2-(CH2)6CH3·2Br-(ii) a The hydrothermal crystallization time temperature is 160 ℃.
The cobalt salt used in example 13 was cobalt nitrate (Co (NO)3)2·6H2O) has a mass of 0.1526 g; the biquaternary ammonium salt template agent is C22H45N+(CH3)2-(CH2)6N+(CH3)2-(CH2)6CH3·2Br-(ii) a The hydrothermal crystallization time temperature is 170 ℃.
The cobalt salt used in example 14 was cobalt chloride (CoCl)2·6H2O) has a mass of 0.0864 g; the biquaternary ammonium salt template agent is C18H37N+(CH3)2-(CH2)4N+(CH3)2-(CH2)6CH3·2Br-(ii) a The hydrothermal crystallization time temperature is 150 ℃.
The cobalt salt used in example 15 was cobalt nitrate (Co (NO)3)2·6H2O) has a mass of 0.1479 g; the biquaternary ammonium salt template agent is C18H37N+(CH3)2-(CH2)4N+(CH3)2-(CH2)6CH3·2Br-(ii) a The hydrothermal crystallization time temperature is 140 ℃.
An SEM picture of the molecular sieve catalyst prepared in example 11 is shown in FIG. 10, and a remarkable lamellar arrangement phenomenon of the powder sieve can be seen, and the lamellar stacking particle size is 6.3 μm;
an SEM picture of the molecular sieve catalyst prepared in example 12 is shown in FIG. 11, and a remarkable lamellar arrangement phenomenon of the powder sieve can be seen, and the lamellar stacking particle size is 6.7 μm;
XRD patterns 12A and 12B of the obtained molecular sieve catalysts prepared in example 11 and example 12 show that the prepared molecular sieves are typical MFI crystal phases according to the comparison of 44-0003 of standard XRD (Jade 6) PDF card, and the cobalt content and the type change of the biquaternary ammonium salt in the precursor solution do not influence the crystal forms.
A TEM image of the molecular sieve catalyst prepared in example 14 is shown in fig. 13, and it can be seen that cobalt oxide is highly uniformly dispersed among the lamellae of the molecular sieve catalyst, and the average particle size of the metal oxide obtained by statistics is 2.58 nm; the molecular sieve catalyst has a surface area of 452m2Per g, pore volume 0.613cm3/g。
[ examples 16 to 20 ]
0.1493g (Al) was taken2(SO4)3·18H2O, 6.0763g of Tetraethylorthosilicate (TEOS), 0.7g of sodium hydroxide (NaOH), and 13.707g H g2Preparing alkaline mixed liquor by using O; 0.4235 concentrated sulfuric acid (H)2SO4，>98 percent), certain mass of ferric salt, certain mass of nickel salt, certain mass of cobalt salt, 2.116g of biquaternary ammonium salt template agent (C)22H45N+(CH3)2-(CH2)6N+(CH3)2-(CH2)6CH3·2Br-) 0.2436gN- [3- (trimethoxysilyl) propyl group]Preparing an acidic mixed solution from ethylenediamine (NMP) and 17.8145g of deionized water, stirring the prepared acidic mixed solution and an alkaline mixed solution at room temperature for 24 hours to obtain a crystallization solution, placing the crystallization solution in a crystallization kettle, and carrying out hydrothermal crystallization at 140 ℃ for 6 days to obtain a hydrothermal crystallization product; the synthesized hydrothermal crystallization productWashing the product powder with deionized water to neutrality, drying at 100 ℃ for 12h, and roasting at 500 ℃ in air atmosphere for 6h to obtain the layered MFI structure molecular sieve catalyst aggregate containing metal oxide nanoparticles.
Weighing 1g of calcined MFI structure molecular sieve catalyst containing metal oxide nanoparticles, adding the calcined MFI structure molecular sieve catalyst into 100mL of 1mol/L ammonium salt solution, stirring for 3h at 85 ℃ for ion exchange treatment, washing with deionized water after the ion exchange treatment is finished, drying for 24h at 100 ℃, calcining for 4h at 550 ℃, and repeating the steps for 3 times; then roasting for 6 hours in the air atmosphere at the temperature of 550 ℃; thus obtaining the layered MFI structure molecular sieve catalyst for encapsulating the metal nano-particles.
Iron salt iron nitrate (Fe (NO))3·6H2O) has a mass of 0.0845 g; ni (NO) used3)2·6H2The mass of O is 0.0862 g; the ammonium salt used is ammonium Nitrate (NH)4NO3)。
Iron salt used in example 17 ferrous nitrate (Fe (NO)2) The mass was 0.1136 g; ni (NO) used3)2·6H2The mass of O is 0.1724 g; the ammonium salt used is ammonium Nitrate (NH)4Cl)。
Iron salt iron chloride (FeCl) used in example 183·6H2O) has a mass of 0.0761 g; ni (NO) used3)2·6H2Mass O0.3448 g; the ammonium salt used is ammonium Nitrate (NH)4NO3)。
Iron salt ferrous chloride (FeCl) used in example 192·4H2O) mass 0.0696 g; cobalt nitrate cobalt (Co (NO) salt used3)2·6H2O) has a mass of 0.1297 g; the ammonium salt used is ammonium Nitrate (NH)4Cl)。
Iron salt iron nitrate (Fe (NO))3·6H2O) has a mass of 0.0845 g; cobalt nitrate cobalt (Co (NO) salt used3)2·6H2O) has a mass of 0.1526 g; the ammonium salt used is ammonium Nitrate (NH)4NO3)。
An SEM image of the molecular sieve catalyst prepared in example 16 is shown in FIG. 14, which shows that the powder sieve has obvious lamellar arrangement, and the lamellar stacking particle size is 3.9 μm;
an SEM picture of the molecular sieve catalyst prepared in example 17 is shown in FIG. 15, which shows that the powder sieve has obvious lamellar arrangement, and the lamellar stacking particle size is 4.6 μm;
a TEM image of the molecular sieve catalyst prepared in example 18 is shown in fig. 16, which shows that iron oxide is highly uniformly dispersed between the sheets of the molecular sieve catalyst, and the average particle size of the metal oxide obtained by statistics is 3.79 nm; the molecular sieve catalyst had a surface area of 492m2Per g, pore volume 0.546cm3/g。
[ example 21 ]
The catalyst obtained in the embodiment 6 is used for catalyzing the cracking reaction of n-heptane, and specifically comprises the following steps of placing 0.5g of the catalyst in a fixed bed reaction tube, raising the temperature of the reaction tube from normal temperature to 550 ℃, pumping in n-heptane 0.2mL/min, introducing nitrogen serving as a carrier gas at a gas flow rate of 50mL/min, detecting a cracking product by using a gas chromatography, and enabling the cracking conversion rate of the n-heptane catalyst obtained in the embodiment 6 to be more than 90%; whereas, using the direct supported control catalyst, the conversion of n-heptane was only 60% under the same conditions, as shown in fig. 17.
The selectivity of propylene in the product can be tested, and the yield of propylene in the cracking product of the catalyst n-heptane obtained in example 6 reaches 30%; above 23% of that obtained using the direct supported control catalyst, as shown in figure 18.
The preparation method of the direct loading type contrast catalyst comprises the following steps: 0.1493g (Al)2(SO4)3·18H2O, 6.0763g of Tetraethylorthosilicate (TEOS), 0.7g of sodium hydroxide (NaOH), and 13.707g H g2Preparing alkaline mixed liquor by using O; 0.4235g concentrated sulfuric acid (H)2SO4，>98 percent), 2.116g of biquaternary ammonium salt template agent (C)22H45N+(CH3)2-(CH2)6N+(CH3)2-(CH2)6CH3·2Br-) 17.8145g of deionized water to obtain an acidic mixed solutionStirring the prepared acidic mixed solution and the prepared alkaline mixed solution for 24 hours at room temperature to obtain a crystallization solution, placing the crystallization solution in a crystallization kettle, and carrying out hydrothermal crystallization for 5 days at the temperature of 140 ℃ to obtain a hydrothermal crystallization product; washing the synthesized hydrothermal crystallization product powder with deionized water to be neutral, drying for 12h at 100 ℃, and roasting for 6h at 500 ℃ in air atmosphere to obtain the layered MFI structure molecular sieve catalyst aggregate (molecular sieve catalyst precursor).
Weighing 1g of calcined layered MFI structure molecular sieve catalyst, and adding 100mL of 1mol/L NH4Stirring the solution in Cl solution at 85 ℃ for 3h for ion exchange treatment, washing the solution with deionized water after the ion exchange treatment is finished, drying the solution at 100 ℃ for 24h, roasting the solution at 550 ℃ for 4h, and repeating the process for 3 times; then roasting for 6 hours in the air atmosphere at 550 ℃; and then reducing the mixture for 2 hours at a constant temperature of 500 ℃ in a hydrogen atmosphere to obtain the H-type layered MFI structure molecular sieve catalyst aggregate (i.e. a molecular sieve catalyst precursor).
0.0845g of iron nitrate (Fe (NO))3·6H2O) is dissolved in 2mL of water to prepare a solution, 1g of the prepared H-shaped sheet layered MFI structure molecular sieve is weighed as a carrier, metal Fe is dispersed on the outer surface of a layered molecular sieve cluster by adopting an isometric impregnation method, the drying is carried out for 12H at the temperature of 100 ℃, the roasting is carried out for 6H at the temperature of 500 ℃ in the air atmosphere, and then the constant temperature reduction is carried out for 2H at the temperature of 500 ℃ in the hydrogen atmosphere, so that the layered MFI structure molecular sieve catalyst with Fe nano particles loaded on the outer surface is prepared.
Industrial applicability
The molecular sieve catalyst provided by the invention can be industrially prepared and can be applied to catalyzing hydrocarbon cracking reaction to prepare low-carbon olefin.
The above examples of the present invention are merely examples for clearly illustrating the present invention and are not intended to limit the embodiments of the present invention. Other variations and modifications will be apparent to persons skilled in the art in light of the above description. And are neither required nor exhaustive of all embodiments. Any modification, equivalent replacement, and improvement made within the spirit and principle of the present invention should be included in the protection scope of the claims of the present invention.

Claims (10)

1. A molecular sieve catalyst, characterized in that the molecular sieve catalyst comprises:
a molecular sieve support comprising agglomerates; the agglomerate comprises a lamellar structure, and a plurality of lamellar structures are stacked to enable the molecular sieve carrier to have a porous structure; and
an active ingredient comprising a metal and/or a metal oxide, the active ingredient having an average particle diameter of 0.5 to 10 nm; wherein
At least 95% or more of the active ingredient, based on the total mass of the active ingredient, is encapsulated between at least two of the lamellar structures of the agglomerate.
2. The molecular sieve catalyst according to claim 1, characterized in that the active ingredient is present in an amount of 0.01 to 10% by mass based on the total mass of the molecular sieve catalyst; and/or
The metal element in the active component is one or the combination of more than two of iron, nickel and cobalt.
3. The molecular sieve catalyst of claim 1 or 2, wherein the individual agglomerates have a particle size of 0.5 to 10 μm; and/or the thickness of the single lamellar structure is 1.4-4 nm.
4. The molecular sieve catalyst of any one of claims 1 to 3, wherein the molecular sieve support is an MFI structure; and/or the surface area of the molecular sieve catalyst is 250-700m2Per g, pore volume of 0.3-0.8cm3/g。
5. A method of preparing a molecular sieve catalyst according to any of claims 1 to 4, comprising the steps of:
preparing a precursor solution containing an active ingredient;
carrying out hydrothermal crystallization treatment on the precursor solution to obtain a hydrothermal crystallization product;
roasting the hydrothermal crystallization product to remove the template agent to obtain a catalyst precursor;
carrying out ion exchange on the catalyst precursor under the condition of having ammonium salt to obtain an ammonium catalyst precursor;
and roasting the ammonium catalyst precursor, and then reducing in a hydrogen atmosphere to obtain the molecular sieve catalyst.
6. The method according to claim 5, wherein the precursor solution is prepared by a method comprising the steps of:
mixing a silicon source, an alkali source and an optional aluminum source in a solvent to obtain an alkaline mixed solution;
mixing a template agent, a metal salt, a complexing agent and an acid source in a solvent to obtain an acidic mixed solution;
and mixing the acidic mixed solution and the alkaline mixed solution to obtain a precursor solution.
7. The method of claim 6, wherein the templating agent comprises a bis-quaternary ammonium salt templating agent; preferably, the biquaternary ammonium salt template agent is CnH2n+1N+(CH3)2-(CH2)mN+(CH3)2-(CH2)kCH3·2Br-Wherein n is an integer of 10 to 30, m is an integer of 1 to 10, and k is an integer of 1 to 10.
8. The method according to claim 6 or 7, wherein the precursor solution contains an alkali source, an acid source, and SiO2Template agent, Al2O3The molar ratio of the active ingredient to the complexing agent to the solvent is (5-60): (2-30): 100: (2-20): (0-50): (1-10): (1-10): (2000-6000).
9. The preparation method according to any one of claims 5 to 8, wherein the temperature of the hydrothermal crystallization treatment is 130 ℃ to 170 ℃, and the time of the hydrothermal crystallization treatment is 2 days to 15 days;
the roasting is carried out in an oxygen-containing atmosphere and/or a hydrogen-containing atmosphere, the roasting temperature is 300-600 ℃, and the roasting time is 4-12 h;
the ion exchange temperature is 50-90 ℃, and the ion exchange time is 2-4 h;
the reduction temperature is 300-700 ℃, and the reduction time is 0.1-5 h.
10. Use of the molecular sieve catalyst according to any one of claims 1 to 4 or the molecular sieve catalyst prepared by the preparation method according to any one of claims 5 to 9 for catalyzing hydrocarbon cracking reaction to prepare light olefins.
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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN115007197A (en) * 2022-06-27 2022-09-06 河南大学 Hierarchical pore ZSM-5 molecular sieve packaged Ni metal catalyst with micropores and mesopores as well as preparation method and application thereof

Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN101462071A (en) * 2007-12-20 2009-06-24 中国石油化工股份有限公司 Catalyst for producing propylene by catalytic pyrolysis and preparation method thereof
JP2013221016A (en) * 2012-04-17 2013-10-28 Mitsui Chemicals Inc Metal-containing zeolite catalyst, and method for producing unsaturated hydrocarbons using the catalyst
CN107020147A (en) * 2017-04-25 2017-08-08 天津大学 A kind of MFI structure sheet molecular sieve catalyst, the preparation method and the usage of package metals oxide or metal nanoparticle
CN108002402A (en) * 2017-12-08 2018-05-08 西北大学 A kind of middle micro-diplopore MFI type nano molecular sieve with multi-layer steamed bread shape pattern and its preparation method and application
CN108579799A (en) * 2018-05-07 2018-09-28 天津大学 MFI structure nano-sheet layer molecular sieve catalyst, preparation method and application thereof
CN111250152A (en) * 2020-03-31 2020-06-09 中国科学院过程工程研究所 Packaging method of Ni @ ZSM-5 bifunctional catalyst
CN111437870A (en) * 2020-04-02 2020-07-24 中国科学院过程工程研究所 Metal @ MFI multi-level pore structure encapsulated catalyst and encapsulation method and application thereof
CN111841623A (en) * 2020-08-19 2020-10-30 河南大学 Molecular sieve catalyst, preparation method and application thereof

Patent Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN101462071A (en) * 2007-12-20 2009-06-24 中国石油化工股份有限公司 Catalyst for producing propylene by catalytic pyrolysis and preparation method thereof
JP2013221016A (en) * 2012-04-17 2013-10-28 Mitsui Chemicals Inc Metal-containing zeolite catalyst, and method for producing unsaturated hydrocarbons using the catalyst
CN107020147A (en) * 2017-04-25 2017-08-08 天津大学 A kind of MFI structure sheet molecular sieve catalyst, the preparation method and the usage of package metals oxide or metal nanoparticle
CN108002402A (en) * 2017-12-08 2018-05-08 西北大学 A kind of middle micro-diplopore MFI type nano molecular sieve with multi-layer steamed bread shape pattern and its preparation method and application
CN108579799A (en) * 2018-05-07 2018-09-28 天津大学 MFI structure nano-sheet layer molecular sieve catalyst, preparation method and application thereof
CN111250152A (en) * 2020-03-31 2020-06-09 中国科学院过程工程研究所 Packaging method of Ni @ ZSM-5 bifunctional catalyst
CN111437870A (en) * 2020-04-02 2020-07-24 中国科学院过程工程研究所 Metal @ MFI multi-level pore structure encapsulated catalyst and encapsulation method and application thereof
CN111841623A (en) * 2020-08-19 2020-10-30 河南大学 Molecular sieve catalyst, preparation method and application thereof

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN115007197A (en) * 2022-06-27 2022-09-06 河南大学 Hierarchical pore ZSM-5 molecular sieve packaged Ni metal catalyst with micropores and mesopores as well as preparation method and application thereof
CN115007197B (en) * 2022-06-27 2024-02-27 河南大学 Multistage hole ZSM-5 molecular sieve encapsulated Ni metal catalyst with micropores and mesopores, and preparation method and application thereof

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