CN110856819A - Surface aluminum-rich molecular sieve, preparation method and application thereof, isomerization reaction catalyst and application thereof - Google Patents

Surface aluminum-rich molecular sieve, preparation method and application thereof, isomerization reaction catalyst and application thereof Download PDF

Info

Publication number
CN110856819A
CN110856819A CN201810974981.8A CN201810974981A CN110856819A CN 110856819 A CN110856819 A CN 110856819A CN 201810974981 A CN201810974981 A CN 201810974981A CN 110856819 A CN110856819 A CN 110856819A
Authority
CN
China
Prior art keywords
molecular sieve
aluminum
crystallization
precursor gel
ratio
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
CN201810974981.8A
Other languages
Chinese (zh)
Other versions
CN110856819B (en
Inventor
李景
赵效洪
朱加清
艾军
李�浩
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
China Energy Investment Corp Ltd
National Institute of Clean and Low Carbon Energy
Original Assignee
China Energy Investment Corp Ltd
National Institute of Clean and Low Carbon Energy
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by China Energy Investment Corp Ltd, National Institute of Clean and Low Carbon Energy filed Critical China Energy Investment Corp Ltd
Priority to CN201810974981.8A priority Critical patent/CN110856819B/en
Publication of CN110856819A publication Critical patent/CN110856819A/en
Application granted granted Critical
Publication of CN110856819B publication Critical patent/CN110856819B/en
Active legal-status Critical Current
Anticipated expiration legal-status Critical

Links

Images

Classifications

    • 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
    • B01J29/70—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof of types characterised by their specific structure not provided for in groups B01J29/08 - B01J29/65
    • B01J29/703—MRE-type, e.g. ZSM-48
    • B01J35/615—
    • B01J35/617—
    • B01J35/643—
    • 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)
    • 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
    • C07C5/22—Preparation of hydrocarbons from hydrocarbons containing the same number of carbon atoms by isomerisation
    • C07C5/27—Rearrangement of carbon atoms in the hydrocarbon skeleton
    • C07C5/2729—Changing the branching point of an open chain or the point of substitution on a ring
    • C07C5/2732—Catalytic processes
    • C07C5/2737—Catalytic processes with crystalline alumino-silicates, e.g. molecular sieves
    • 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
    • C07C5/22—Preparation of hydrocarbons from hydrocarbons containing the same number of carbon atoms by isomerisation
    • C07C5/27—Rearrangement of carbon atoms in the hydrocarbon skeleton
    • C07C5/2767—Changing the number of side-chains
    • C07C5/277—Catalytic processes
    • C07C5/2775—Catalytic processes with crystalline alumino-silicates, e.g. molecular sieves
    • 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

Landscapes

  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Catalysts (AREA)
  • Low-Molecular Organic Synthesis Reactions Using Catalysts (AREA)

Abstract

The invention relates to the field of molecular sieves, and discloses a preparation method of a molecular sieve with an aluminum-rich surface. The obtained molecular sieve has high crystallinity, effective acid centers are intensively distributed on the outer surface, and high catalytic activity and high catalytic selectivity are shown in long-chain alkane isomerization catalytic reaction.

Description

Surface aluminum-rich molecular sieve, preparation method and application thereof, isomerization reaction catalyst and application thereof
Technical Field
The invention relates to the field of molecular sieves, in particular to a molecular sieve with an aluminum-rich surface, a preparation method and application thereof, an isomerization catalyst and application thereof.
Background
Molecular sieves are commonly used as catalysts or catalyst supports due to their pore structure. Of these, molecular sieves such as ZSM-5, ZSM-12, ZSM-22, ZSM-23, ZSM-48 and SSZ-32 are used in larger amounts. ZSM-48 is a kind of high silicon zeolite, belonging to orthorhombic system structure, having 10-membered open pore non-through interlaced linear pore canal, the pore canals are connected by 5-membered ring, the pore diameter is 0.53nm x 0.56 nm. Generally, pure silicon ZSM-48 molecular sieve has good selectivity of low carbon olefin and low silicon-aluminum ratio (SiO) in the reaction of preparing olefin from synthesis gas2/Al2O3) The ZSM-48 molecular sieve has good isomerization cracking catalytic performance.
"Synthesis and characterization of high-silica zeolite ZSM-48" (Natural gas chemical, 1993, 18 (1): 8-12) discloses a method for preparing high-silica zeolite ZSM-48 by using 1, 6-hexamethylenediamine as a structure directing agent through hydrothermal crystallization, wherein the used raw materials are silica sol, NaOH, 1, 6-hexamethylenediamine and deionized water. Adding the reactants into a 100mL stainless steel high-pressure synthesis kettle according to a certain proportion and sequence, stirring for 10-15min, sealing, standing at 185 ℃ for crystallization until crystallization is completed, wherein the crystallization time is selected according to the temperature. After separation, washing and drying, NaZSM-48 raw powder is obtained, but the synthesis and the application of aluminum-containing ZSM-48 are not involved in the text. The synthesized ZSM-48 molecular sieve with high silica-alumina ratio has too large and aggregated crystal grains, large crystal grain size and poor catalyst performance; high water content and low single-kettle yield.
The synthesis and characterization of the ZSM-48 molecular sieve with the low silica alumina ratio (modern chemical industry, 2014, 34, 3:97-102) discloses a synthesis method of the ZSM-48 molecular sieve with the low silica alumina ratio. Through orthogonal experimental design, the influence of various factors on the synthesis of the ZSM-48 is researched, the synthesis system of the ZSM-48 molecular sieve with the low silica-alumina ratio is optimized by changing the using amounts of the template agent, the silicon source, the alkali source and the water, and the ZSM-48 molecular sieve with the silica-alumina ratio as low as 56.7 is finally prepared, however, the test result shows that the ZSM-48 with the low silica-alumina ratio is in a rod-shaped and sheet-shaped conglomerate form and has lower relative crystallinity.
Applicants have found that high silica ZSM-48 molecular sieves have too low activity in isomerization catalysis, while low silica-alumina ratio ZSM-48 molecular sieves have poor isomerization selectivity despite improved catalytic activity. At present, a plurality of synthesis methods of ZSM-48 molecular sieves are reported in documents, but the obtained molecular sieves cannot realize the joint optimization of catalytic activity and isomeric selectivity, namely, higher catalytic activity is obtained and higher selectivity is ensured.
The applicant has also found that during the isomerization of long paraffins, the framework aluminium content on the molecular sieve, corresponding to the framework acidity, determines the catalytic activity. On the premise of no change of metal functions, the addition of acid functions (low silicon-aluminum ratio) is beneficial to improving the conversion rate of raw materials but not beneficial to isomerization rate; reducing the acid function (high silica to alumina ratio) reduces the undesirable cracking reactions, but at the same time reduces the conversion of the feedstock and reduces the catalytic activity. The molecular sieve synthesized by the conventional method usually cannot have the balance between activity and selectivity, which is mainly because the acid centers of the molecular sieve synthesized by one-time crystallization are unreasonably distributed, and the inner surface of the molecular sieve contains aluminum acid sites, so that the isomeric products are easy to further crack and lose.
Therefore, there is a need for a method for preparing a molecular sieve having sufficient aluminate sites on the surface and no or less framework aluminate sites on the inner surface, so as to avoid or reduce side reactions caused by the framework aluminate sites on the inner surface of the molecular sieve while ensuring the catalytic activity of the surface.
Disclosure of Invention
The invention aims to solve the problem that high activity and high isomerization selectivity cannot be simultaneously obtained when a molecular sieve is used for long-chain alkane isomerization conversion in the prior art, and provides a surface aluminum-rich molecular sieve, a preparation method and application thereof, an isomerization reaction catalyst and application thereof.
In order to achieve the above object, a first aspect of the present invention provides a method for preparing a surface aluminum-rich molecular sieve, the method comprising:
(1) preparing a precursor gel A, B, wherein the silicon-aluminum ratio of the precursor gel A is 40-100, the silicon-aluminum ratio of the precursor gel B is 100-400, and the silicon-aluminum ratios of the precursor gel A and the precursor gel B are different;
(2) respectively carrying out first-step crystallization on the precursor gels A, B;
(3) respectively preparing a first-step crystallization product from the precursor gel A, B according to a mass ratio of 1: (3-50) mixing and carrying out second-step crystallization to finally prepare the surface aluminum-rich molecular sieve.
In a second aspect, the present invention provides a surface aluminum-rich molecular sieve produced by the process of the first aspect of the present invention.
In a third aspect, the invention provides the use of a molecular sieve according to the second aspect of the invention in a catalytic reaction.
In a fourth aspect, the present invention provides an isomerisation reaction catalyst comprising a binder, a metal active component and a molecular sieve according to the second aspect of the invention.
In a fifth aspect, the present invention provides the use of an isomerisation reaction catalyst according to the fourth aspect of the invention in an isomerisation reaction of a hydrocarbon.
The invention prepares two molecular sieve precursor gels with different silicon-aluminum ratios, the silicon-aluminum ratio is in the range of 40-400, and the molecular sieve precursor gels are respectively crystallized for a period of time through fractional crystallization to obtain semi-crystallized or completely crystallized products, and then the semi-crystallized or completely crystallized products are mixed according to a certain proportion and are crystallized for a period of time again to obtain the molecular sieve with controllable acid distribution and gradient distribution of aluminum element from outside to inside.
The method can be used for synthesizing the ZSM-48 molecular sieve and also can be used for synthesizing the ZSM-5, ZSM-12, ZSM-22, ZSM-23, ZSM-48 and SSZ-32 molecular sieves, the obtained molecular sieve not only has high crystallinity, but also has effective acid centers which are intensively distributed on the outer surface, thereby avoiding the adverse effect caused by the acid centers on the inner surface, and having higher isomeric selectivity while keeping high catalytic activity. The surface aluminum-rich molecular sieve has good application prospect in the fields of preparing low-carbon olefin from synthesis gas, isomerizing normal paraffin and preparing lubricating oil base oil and the like from wax oil through hydroisomerization.
Drawings
FIG. 1 is a Transmission Electron Microscope (TEM) section analysis of the molecular sieve described in example 2.
FIG. 2 is a TEM section analysis of the molecular sieve described in example 2 showing the silicon to aluminum ratio over a 200nm thickness range on the surface.
Detailed Description
The endpoints of the ranges and any values disclosed herein are not limited to the precise range or value, and such ranges or values should be understood to encompass values close to those ranges or values. For ranges of values, between the endpoints of each of the ranges and the individual points, and between the individual points may be combined with each other to give one or more new ranges of values, and these ranges of values should be considered as specifically disclosed herein.
The invention provides a preparation method of a surface aluminum-rich molecular sieve in a first aspect, which comprises the following steps:
(1) preparing a precursor gel A, B, wherein the silicon-aluminum ratio of the precursor gel A is 40-100, the silicon-aluminum ratio of the precursor gel B is 100-400, and the silicon-aluminum ratios of the precursor gel A and the precursor gel B are different;
(2) respectively carrying out first-step crystallization on the precursor gels A, B;
(3) respectively preparing a first-step crystallization product from the precursor gel A, B according to a mass ratio of 1: (3-50) mixing and carrying out second-step crystallization to finally prepare the surface aluminum-rich molecular sieve.
As used herein, the Si/Al ratio refers to the molar ratio of silica to alumina.
In the present invention, the silica-alumina ratio of the precursor gel a may be any value in the range of 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95 and 100 and any two of the above values, and preferably, the silica-alumina ratio of the precursor gel a is 50 to 100.
In the present invention, the silica-alumina ratio of the precursor gel B may be any value in the range of 105, 110, 120, 150, 170, 200, 230, 250, 270, 300, 320, 350, 380 and 400 and any two of the above values, preferably, the silica-alumina ratio of the precursor gel B is 150-.
In the present invention, in step (1), the precursor gel A, B is prepared from a template, a silicon source, an aluminum source, water and sodium hydroxide, respectively.
In the present invention, in the precursor gel a, the molar ratio of the silicon source, the aluminum source, the water, the alkali and the template agent is 1: (0.01-0.025): (10-40): (0.11-0.19): (0.0175-0.0215), preferably 1: (0.015-0.025): (20-40): (0.14-0.19): (0.0195 to 0.0215), more preferably 1: (0.015-0.02): (20-30): (0.15-0.17): (0.0195-0.0215). The silicon source is SiO2The aluminum source is calculated as Al2O3Calculated as OH, the base-And (6) counting.
In the precursor gel B, the molar ratio of the silicon source, the aluminum source, the water, the alkali and the template agent is 1: (0.0025-0.01): (10-40): (0.11-0.19): (0.0175-0.0215), preferably 1: (0.0025-0.008): (10-20): (0.11-0.15): (0.0175-0.0195), more preferably 1: (0.0035-0.005): (10-20): (0.13-0.15): (0.0175-0.0195). The silicon source is SiO2The aluminum source is calculated as Al2O3Calculated as OH, the base-And (6) counting.
In the present invention, the silicon source and the aluminum source used can be selected according to the prior art, for example, the silicon source can be silica sol, solid silica gel, sodium silicate, tetraethyl silicate, etc., and the aluminum source can be sodium metaaluminate, aluminum sulfate, aluminum chloride, aluminum sol, etc. According to a preferred embodiment, the silicon source is silica sol and the aluminium source is sodium metaaluminate. The content of silica in the silica sol can be selected according to the actual need, for example, from 20 to 40 wt%.
In the present invention, the base may be selected according to the prior art. Preferably, the base is an alkali metal and/or alkaline earth metal hydroxide, such as at least one of sodium hydroxide, potassium hydroxide and calcium hydroxide.
In the present invention, the template may be selected according to the molecular sieve to be prepared. In one embodiment of the present invention, the template is selected from at least one of 1, 6-hexanediamine, 1, 8-octanediamine and hexamethonium bromide, and the molecular sieve prepared using the above template is a ZSM-48 molecular sieve.
In the present invention, in step (2), the first crystallization process of precursor gel a crystallizes the precursor gel a for a period of time to obtain a gel state in an amorphous state before the crystal phase is formed, so that the crystallization conditions can be adjusted according to actual operating conditions, for example, the conditions of the first crystallization of precursor gel a include: the temperature is 150-190 ℃, and preferably 150-160 ℃; the time is 3 to 120 hours, preferably 4 to 24 hours, more preferably 8 to 16 hours.
In the present invention, in the step (2), the first crystallization process of the precursor gel B is performed for crystallization for a certain period of time to obtain a gel state forming a crystal phase, so that the crystallization conditions can be adjusted according to actual operating conditions, for example, the conditions of the first crystallization of the precursor gel B include: the temperature is 150-190 ℃, and preferably 150-160 ℃; the time is 3 to 120 hours, preferably 12 to 48 hours, more preferably 16 to 32 hours.
In the invention, in the step (3), the first-step crystallization product of the precursor gel A, B is mixed according to a certain mass ratio to carry out the second-step crystallization. The mixing ratio of the first-step crystallization product of precursor gel A, B can be adjusted according to the silicon-aluminum ratio of A, B, the condition of the first-step crystallization, and the like, and for example, may be 1:3, 1:5, 1:10, 1:15, 1:20, 1:25, 1:30, 1:35, 1:40, 1:45, and 1:50, and preferably, the mass ratio of the first-step crystallization product of precursor gel A, B is 1: (5-30); more preferably 1: (5-20).
In the present invention, the first-step crystallization product of the precursor gel A, B is mixed according to the above ratio, and then the second-step crystallization is performed. The conditions of the second step crystallization comprise: the temperature is 150-190 ℃, preferably 160-170 ℃; the time is 6-48h, preferably 8-12 h.
In the present invention, the first crystallization and the second crystallization are performed in a reactor, which may be, for example, a reaction vessel or a crystallization vessel. The first and second crystallization steps may be selected from dynamic or static crystallization, respectively. In the invention, the static crystallization refers to that no stirring process or mixing process similar to stirring exists in the system in the crystallization process; the dynamic crystallization refers to that a stirring process or a mixing process similar to stirring always exists in a system in the crystallization process.
In the present invention, preferably, the first crystallization step of precursor gel A, B is dynamic crystallization. Also, the second crystallization step of the mixture of the first crystallization step products of the precursor gel A, B is a static crystallization. During the first dynamic crystallization step of the precursor gel A, B, the stirring speed can be adjusted as required, for example, at 100-.
In the invention, after the second step of crystallization, the obtained product is separated, washed, dried, ammonium-exchanged and roasted to prepare the molecular sieve with aluminum-enriched surface. The specific operations of separating, washing, drying, ammonium exchange and roasting can be selected according to the prior art, for example, the separating and washing adopts a vacuum filtration method or a centrifugal washing method until the pH of the filtrate is reduced to below 10; ammonium nitrate solution with the concentration of 1mol/L is adopted for stirring treatment for 1 hour at the temperature of 80 ℃, and the filtration and the washing are repeated for 2 to 3 times; the roasting is carried out for 4 hours at 550 ℃ in an air atmosphere.
In a second aspect, the present invention provides a surface-enriched aluminum molecular sieve prepared by the method of the first aspect, wherein the molecular sieve can be any one of ZSM-5, ZSM-12, ZSM-22, ZSM-23, ZSM-48 or SSZ-32 molecular sieves.
According to one embodiment, the ZSM-48 molecular sieve is prepared by the method, the silicon-aluminum ratio of the whole molecular sieve is 150-300, and the silicon-aluminum ratio of the particle surface of the molecular sieve in the thickness of 50nm is 40-150, preferably 40-90. The expression "within 50nm of the thickness of the particle surface" is understood here to mean a thickness range of 50nm from the particle surface.
According to one embodiment, the method produces molecular sieves having a specific surface area of not less than 200m2Per g, preferably 200-2(ii)/g; the aperture is 0.53-0.56 nm; pore volume of not less than 0.1cm3In g, preferably from 0.1 to 1cm3/g。
In the invention, the molecular sieve prepared by the method has high crystallinity which is more than 98 percent.
In a third aspect, the present invention provides the use of a molecular sieve according to the second aspect of the invention in a catalytic reaction.
In a fourth aspect, the present invention provides an isomerisation reaction catalyst comprising a molecular sieve according to the second aspect of the invention.
In one embodiment of the invention, the catalyst further comprises a binder and a metal active component, the metal active component being selected according to the prior art, for example one or more selected from Pt, Pd and Ni, and the binder being selected according to the prior art, for example alumina or silica.
In the present invention, the isomerization catalyst comprises the molecular sieve prepared by the method of the first aspect of the present invention, which has a high crystallinity (98% or more) and a gradient decrease in the distribution of aluminum element from the outside to the inside, and has such a structure and composition that a high catalytic activity and a high isomerization selectivity can be simultaneously obtained in the isomerization of long-chain alkane (having 10 or more carbon atoms, such as n-dodecane or n-hexadecane).
In a fifth aspect, the present invention provides the use of an isomerisation reaction catalyst according to the fourth aspect of the invention in an isomerisation reaction of a hydrocarbon.
The present invention will be described in detail below by way of examples.
Example 1
(1) Dissolving 7.78g of hexamethonium bromide, 3.28g of sodium metaaluminate and 6g of sodium hydroxide in 540g of water to form a solution; 200g of silica sol (with the concentration of 30 wt%) is slowly added into the solution of the system under stirring and stirred uniformly to prepare a molecular sieve precursor gel A, wherein SiO is used2：Al2O3：H2O：OH-: the molar ratio of the ammonium hexametaphosphate to the ammonium hexametaphosphate is 1:0.02:30:0.15: 0.0215;
(2) 6.34g of hexamethonium bromide, 0.82g of metaaluminic acidSodium, 5.2g of sodium hydroxide, dissolved in 270g of water to form a solution; 200g of silica sol (with the concentration of 30 wt%) is slowly added into the solution of the system under stirring and stirred uniformly to prepare a molecular sieve precursor gel B, wherein SiO is used2：Al2O3：H2O：OH-: the molar ratio of the ammonium hexamethobromide is 1:0.005:15:0.13: 0.0175;
(3) putting the molecular sieve precursor gel A, B into different reaction kettles, sealing, and crystallizing for 12 hours by performing first-step crystallization on A at the temperature of 150 ℃ and the rotating speed of 500 rpm; b, performing first-step crystallization at 160 ℃ and at the rotating speed of 500rpm for 24 hours;
(4) cooling the reaction kettle to below 100 ℃, then mixing A, B first-step crystallization products according to the mass ratio of 1:5, uniformly stirring, carrying out second-step crystallization at 170 ℃, statically crystallizing for 12 hours, filtering, washing, drying and carrying out ammonium exchange on the obtained products, roasting for 4 hours at 550 ℃, and obtaining the molecular sieve with the crystallinity of 98%, which is marked as A1.
Example 2
The molecular sieve was prepared as described in example 1 except that A, B was mixed in the first step of crystallization at a mass ratio of 1:10 and then subjected to the second step of crystallization to finally obtain molecular sieve having a crystallinity of 99%, designated as a 2.
Example 3
The molecular sieve was prepared as described in example 1 except that A, B was mixed in the first crystallization step at a mass ratio of 1:20 and then subjected to the second crystallization step to finally obtain a molecular sieve having a crystallinity of 98%, designated as A3.
Example 4
The molecular sieve was prepared as described in example 1 except that A, B was mixed in the first crystallization step at a mass ratio of 1:30 and then subjected to the second crystallization step to finally obtain a molecular sieve having a crystallinity of 98%, designated as a 4.
Example 5
The molecular sieve was prepared as described in example 1 except that A, B was mixed in the first crystallization step at a mass ratio of 1:50 and then subjected to the second crystallization step to finally obtain a molecular sieve having a crystallinity of 98%, designated as a 5.
Example 6
Molecular sieves were prepared as described in example 1, except that in step (4), A was subjected to a first crystallization step at 150 ℃ and 500rpm for 24h to finally obtain molecular sieves having a crystallinity of 98%, designated A6.
Comparative example 1
Molecular sieves were prepared as described in example 1, except that the A, B first step crystallized product was mixed in a mass ratio of 1:80 to finally produce molecular sieves with a crystallinity of 96%, designated as D1.
Comparative example 2
Molecular sieves were prepared as described in example 1, except that the product of the first crystallization step of A, B was separately crystallized for 12h under the conditions of the second crystallization step described in example 1; and mixing the crystallized products according to the mass ratio of 1:5 to finally prepare the molecular sieve, wherein the crystallinity is 91 percent and is marked as D2.
Example 7
(1) Dissolving 7.78g of hexamethonium bromide, 1.64g of sodium metaaluminate and 6g of sodium hydroxide in 540g of water to form a solution; 200g of silica sol (with the concentration of 30 wt%) is slowly added into the solution of the system under stirring and stirred uniformly to prepare a molecular sieve precursor gel A, wherein SiO is used2：Al2O3：H2O：OH-: the molar ratio of the ammonium hexametaphosphate to the ammonium hexametaphosphate is 1:0.01:30:0.15: 0.0215;
(3) molecular Sieve precursor gel B was prepared in the same manner as in example 1, wherein SiO was used2：Al2O3：H2O：OH-: the molar ratio of the ammonium hexamethobromide is 1:0.005:15:0.13: 0.0175;
(4) respectively putting the molecular sieve precursor gel A, B into a reaction kettle, sealing, performing first-step crystallization for 10 hours at the temperature of 150 ℃ and the rotating speed of 500rpm, and performing first-step crystallization for 24 hours at the temperature of 160 ℃ and the rotating speed of 500 rpm;
(5) cooling the reaction kettle to below 100 ℃, mixing A, B first-step crystallization products according to the mass ratio of 1:10, uniformly stirring, statically crystallizing at 165 ℃ for 12 hours again, filtering, washing, drying and ammonium-crosslinking the final product, and roasting at 550 ℃ for 4 hours to obtain the molecular sieve, wherein the crystallinity is 98%, and is recorded as A7.
Comparative example 3
The molecular sieve is prepared by referring to the method described in example 5, except that the molecular sieve precursor gel with the silica-alumina ratio of 162 is directly prepared, and is statically crystallized for 12 hours at 165 ℃, so that the final product is directly obtained, and the molecular sieve is obtained by filtering, washing, drying, ammonium exchange and roasting, and the crystallinity degree is 95%, and is marked as D3.
Example 8
(1) Dissolving 7.06g of hexamethonium bromide, 3.28g of sodium metaaluminate and 6g of sodium hydroxide in 540g of water to form a solution; 200g of silica sol (with the concentration of 30 wt%) is slowly added into the solution of the system under stirring and stirred uniformly to prepare a molecular sieve precursor gel A, wherein SiO is used2：Al2O3：H2O：OH-: the molar ratio of the ammonium hexametaphosphate to the ammonium hexametaphosphate is 1:0.02:25:0.17: 0.0195;
(3) dissolving 6.34g of hexamethonium bromide, 0.41g of sodium metaaluminate and 5.2g of sodium hydroxide in 270g of water to form a solution; 200g of silica sol (concentration: 30 wt%) was slowly added to the solution of system (1) with stirring and stirred uniformly to prepare molecular sieve precursor gel A in which SiO was used2：Al2O3：H2O：OH-: the molar ratio of the ammonium hexametaphosphate to the ammonium hexametaphosphate is 1:0.0025:20:0.15: 0.0195;
(4) respectively putting the molecular sieve precursor gel A, B into a reaction kettle, sealing, performing first-step crystallization for 15h at 150 ℃ and 500rpm, and performing first-step crystallization for 20h at 170 ℃ and 500 rpm;
(5) and (3) cooling, mixing the A, B first-step crystallization products according to the mass ratio of 1:10, uniformly stirring, statically crystallizing at 170 ℃ for 12 hours again, filtering, washing and drying the final product, performing ammonium cross-linking, and roasting at 550 ℃ for 4 hours to obtain the molecular sieve, wherein the crystallinity is 98%, and is recorded as A8.
Test example
1. XRD test
XRD tests are respectively carried out on the molecular sieves A1-A8 and D1-D3 obtained in examples 1-8 and comparative examples 1-3, and the tests show that XRD characteristic peaks of all samples belong to MRE topological structures (space structure codes of ZSM-48 molecular sieves), which indicates that the molecular sieves A1-A8 and D1-D3 are both ZSM-48 molecular sieves, and the crystallinity of the molecular sieves A1-A8 is more than 98%.
2. X-ray fluorescence Spectroscopy (XRF) testing
The molecular sieves a1-A8 and D1-D3 obtained in examples 1 to 8 and comparative examples 1 to 3 were subjected to XRF testing, and elemental composition tests of the molecular sieves were examined, and the results are shown in table 1 as a whole of silicon to aluminum ratio.
TABLE 1
Figure BDA0001777191970000121
3. Distribution test of Al element
The molecular sieves A1-A8 and D1-D3 obtained in examples 1-8 and comparative examples 1-3 were examined by Transmission Electron Microscope (TEM) section analysis, and the distribution of Al element in the molecular sieves from the outside to the inside was examined, and the results are shown in Table 1 as the Si/Al ratio in a thickness of 50nm on the surface. The molecular sieve of example 2 is shown in a TEM section analysis and detection diagram in FIG. 1, and the molecular sieve of example 2 has a Si/Al ratio in a surface thickness range of 200nm in FIG. 2, and it can be seen from FIG. 2 that Al element in the molecular sieve is distributed in a gradient manner.
4. Testing of specific surface area and pore volume
The specific surface areas and pore volumes of the molecular sieves A1-A8 and D1-D3 were tested by a low temperature liquid nitrogen physical adsorption method, and the test results are shown in Table 1.
5. Testing of skeleton acidity
Taking a molecular sieve sample of 20mg, tabletting with diameter of 1.3cm, placing into an infrared test sample cell, and vacuumizing to 10%-3Heating to 400 deg.C below Pa for 30min, adsorbing pyridine at room temperature, vacuum desorbing, keeping the temperature at 350 deg.C to reach desorption balance, measuring infrared signal, subtracting background signal, and calculating to obtain final acid amount (refer to "Preparation ofthesurface Ti,Al rich ETS-10 and modification of its pore structure and aciditybydesilication and realumination”，Microporous and Mesoporous Materials,Volume 145,Pages 224-230)。
Catalyst preparation and isomerization reaction testing
The catalyst is prepared according to the method disclosed in US8790507B2, and the composition ratio of the catalyst is as follows: alumina: pt 65:35: 0.35.
The isomerization test of the catalyst is carried out on a micro-reaction device, n-hexadecane is taken as a model compound, the reaction conditions are normal pressure, the hydrogen-oil ratio is 500:1, and the mass space velocity is 2.3h-1The overall conversion was adjusted to 94% with a change in temperature and the isohexadecane selectivity data was tested at an overall conversion of 94%, with the results shown in table 2.
TABLE 2
The results in table 2 show that the examples of the present invention have significantly better effects, and the samples obtained by the examples of the present invention have lower reaction temperature under the same conversion rate, which indicates higher catalyst activity, wherein the reaction temperatures of a1, a2, a7 and A8 do not exceed 290 ℃, and the isomerization selectivity is higher than 95%.
The preferred embodiments of the present invention have been described above in detail, but the present invention is not limited thereto. Within the scope of the technical idea of the invention, many simple modifications can be made to the technical solution of the invention, including combinations of various technical features in any other suitable way, and these simple modifications and combinations should also be regarded as the disclosure of the invention, and all fall within the scope of the invention.

Claims (12)

1. A method for preparing a surface aluminum-rich molecular sieve, the method comprising:
(1) preparing a precursor gel A, B, wherein the silicon-aluminum ratio of the precursor gel A is 40-100, the silicon-aluminum ratio of the precursor gel B is 100-400, and the silicon-aluminum ratios of the precursor gel A and the precursor gel B are different;
(2) respectively carrying out first-step crystallization on the precursor gels A, B;
(3) respectively preparing a first-step crystallization product from the precursor gel A, B according to a mass ratio of 1: (3-50) mixing and carrying out second-step crystallization to finally prepare the molecular sieve with the aluminum-rich surface.
2. The method of claim 1, wherein in step (1), the precursor gel A, B is prepared from a templating agent, a silicon source, an aluminum source, water, and sodium hydroxide, respectively.
3. The method of claim 2, wherein the molar ratio of the silicon source, the aluminum source, the water, the base, and the templating agent in the precursor gel a is 1: (0.01-0.025): (10-40): (0.11-0.19): (0.0175-0.0215);
in the precursor gel B, the molar ratio of the silicon source, the aluminum source, the water, the alkali and the template agent is 1: (0.0025-0.01): (10-40): (0.11-0.19): (0.0175-0.0215);
wherein the silicon source is SiO2The aluminum source is calculated as Al2O3Calculated as OH, the base-And (6) counting.
4. The process of claim 2 or 3, wherein the silicon source is silica sol and the aluminum source is sodium metaaluminate.
5. The method of claim 1, wherein in step (2), the conditions for the first crystallization of the precursor gel a comprise: the temperature is 150-190 ℃, and preferably 150-160 ℃; the time is 3 to 120 hours, preferably 4 to 24 hours, more preferably 8 to 16 hours.
6. The method of claim 1, wherein in step (2), the first crystallization conditions of the precursor gel B comprise: the temperature is 150-190 ℃, and preferably 150-160 ℃; the time is 3 to 120 hours, preferably 12 to 48 hours, more preferably 16 to 32 hours.
7. The method of claim 1, wherein the conditions of the second crystallization step include: the temperature is 150 ℃ and 190 ℃, and the time is 6-48h, more preferably 8-12 h.
8. A surface aluminum rich molecular sieve produced by the process of any of claims 1 to 7.
9. The molecular sieve of claim 8, wherein the molecular sieve is a ZSM-48 molecular sieve, the silica/alumina ratio of the surface of the particles of the molecular sieve within 50nm of the thickness is 40-150, preferably 40-90, and the silica/alumina ratio of the whole molecular sieve is 150-300.
10. Use of the molecular sieve of claim 8 or 9 in a catalytic reaction.
11. An isomerization catalyst comprising a binder, a metal active component and the molecular sieve of claim 8 or 9.
12. Use of the isomerization catalyst of claim 11 in an isomerization of a hydrocarbon.
CN201810974981.8A 2018-08-24 2018-08-24 Surface aluminum-rich molecular sieve, preparation method and application thereof, isomerization reaction catalyst and application thereof Active CN110856819B (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN201810974981.8A CN110856819B (en) 2018-08-24 2018-08-24 Surface aluminum-rich molecular sieve, preparation method and application thereof, isomerization reaction catalyst and application thereof

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN201810974981.8A CN110856819B (en) 2018-08-24 2018-08-24 Surface aluminum-rich molecular sieve, preparation method and application thereof, isomerization reaction catalyst and application thereof

Publications (2)

Publication Number Publication Date
CN110856819A true CN110856819A (en) 2020-03-03
CN110856819B CN110856819B (en) 2022-07-26

Family

ID=69636273

Family Applications (1)

Application Number Title Priority Date Filing Date
CN201810974981.8A Active CN110856819B (en) 2018-08-24 2018-08-24 Surface aluminum-rich molecular sieve, preparation method and application thereof, isomerization reaction catalyst and application thereof

Country Status (1)

Country Link
CN (1) CN110856819B (en)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN111573694A (en) * 2020-06-17 2020-08-25 浙江大学 Method for synthesizing aluminum-enriched MRE zeolite molecular sieve by organic template in one step
CN114436279A (en) * 2021-12-15 2022-05-06 国家能源集团宁夏煤业有限责任公司 ZSM-22 molecular sieve, preparation method and application thereof, and n-dodecane isomerization reaction

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5254327A (en) * 1992-04-03 1993-10-19 Intevep, S.A. Zeolitic catalyst of MFI type, its preparation and use
CN1363517A (en) * 2000-12-19 2002-08-14 普莱克斯技术有限公司 Synthesis of aluminium riched AFI zeolite
CN101096274A (en) * 2006-06-29 2008-01-02 中国石油化工股份有限公司 Preparation method of aluminum-enriched beta zeolite
CN101274764A (en) * 2007-03-30 2008-10-01 中国石油化工股份有限公司 Preparation for nanometer allitic beta-zeolite
CN102616807A (en) * 2012-03-29 2012-08-01 北京化工大学 Method for synthesizing Y type molecular sieve
CN103803576A (en) * 2012-11-07 2014-05-21 中国石油化工股份有限公司 ZSM-48 molecular sieve with low silica-alumina ratio and preparation method thereof
CN105967202A (en) * 2016-05-03 2016-09-28 太原理工大学 Synthetic method of ZSM-48 molecular sieve with low silica-alumina ratio

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5254327A (en) * 1992-04-03 1993-10-19 Intevep, S.A. Zeolitic catalyst of MFI type, its preparation and use
CN1363517A (en) * 2000-12-19 2002-08-14 普莱克斯技术有限公司 Synthesis of aluminium riched AFI zeolite
CN101096274A (en) * 2006-06-29 2008-01-02 中国石油化工股份有限公司 Preparation method of aluminum-enriched beta zeolite
CN101274764A (en) * 2007-03-30 2008-10-01 中国石油化工股份有限公司 Preparation for nanometer allitic beta-zeolite
CN102616807A (en) * 2012-03-29 2012-08-01 北京化工大学 Method for synthesizing Y type molecular sieve
CN103803576A (en) * 2012-11-07 2014-05-21 中国石油化工股份有限公司 ZSM-48 molecular sieve with low silica-alumina ratio and preparation method thereof
CN105967202A (en) * 2016-05-03 2016-09-28 太原理工大学 Synthetic method of ZSM-48 molecular sieve with low silica-alumina ratio

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN111573694A (en) * 2020-06-17 2020-08-25 浙江大学 Method for synthesizing aluminum-enriched MRE zeolite molecular sieve by organic template in one step
CN111573694B (en) * 2020-06-17 2021-10-15 浙江大学 Method for synthesizing aluminum-enriched MRE zeolite molecular sieve by organic template in one step
CN114436279A (en) * 2021-12-15 2022-05-06 国家能源集团宁夏煤业有限责任公司 ZSM-22 molecular sieve, preparation method and application thereof, and n-dodecane isomerization reaction

Also Published As

Publication number Publication date
CN110856819B (en) 2022-07-26

Similar Documents

Publication Publication Date Title
CN106513035A (en) Preparation method for mesoporous-microporous composite hydroisomerization dewaxing catalyst
CN105032478B (en) A kind of catalyst and its dedicated core-shell structure compound molecular sieve for the oily isomerization-visbreaking of F-T synthetic middle distillates point
CN105817260B (en) Method for synthesizing FER/MOR eutectic molecular sieve
CN112678842B (en) Synthesis method of nano Sn-Beta molecular sieve
CN105417552A (en) Hierarchical porous SAPO-18 molecular sieve, preparation method thereof and application thereof
CN107487777A (en) The synthetic method of the nanometer molecular sieve catalysts of HZSM 5
CN110856819B (en) Surface aluminum-rich molecular sieve, preparation method and application thereof, isomerization reaction catalyst and application thereof
WO2016145619A1 (en) Method for preparation of, and application of, mordenite having mesopores and micropores
CN112645349A (en) Preparation method and application of mordenite molecular sieve
CN111137905A (en) ZSM-48 molecular sieve and preparation method thereof
CN105645427B (en) The preparation method of the molecular sieves of ZSM 22 with mesoporous micropore graded structure
CN114014334A (en) Medium silicon-aluminum ratio ZSM-5 heterozygous nanosheet molecular sieve and preparation method thereof
CN106904629B (en) SAPO-34 multistage porous molecular sieve of nanometer sheet vortex shape self assembly and preparation method thereof
CN105645428B (en) The preparation method of the molecular sieves of SSZ 32 with mesoporous micropore graded structure
CN110642266B (en) ZSM-48 molecular sieve and preparation method and application thereof
CN103466654B (en) Preparation method of ZSM-5 mesoporous and microporous composite molecular sieve
CN114436279A (en) ZSM-22 molecular sieve, preparation method and application thereof, and n-dodecane isomerization reaction
CN112661166B (en) Hierarchical pore Y-type molecular sieve and preparation method and application thereof
CN110342533B (en) Molecular sieve and preparation method and application thereof
CN111689505A (en) Preparation method of ZSM-5 molecular sieve with mesoporous-microporous hierarchical structure
CN109704358B (en) Synthesis method of EU-1/ZSM-5 composite molecular sieve
CN104588091B (en) A kind of Beta and the composite molecular screens of EU 1 and its synthetic method
CN112619694A (en) Process for preparing olefin catalyst
CN113860323B (en) Synthesis method of molecular sieve
CN111410207B (en) Normal-pressure synthesis method of SAPO-11 molecular sieve

Legal Events

Date Code Title Description
PB01 Publication
PB01 Publication
SE01 Entry into force of request for substantive examination
SE01 Entry into force of request for substantive examination
CB02 Change of applicant information
CB02 Change of applicant information

Address after: 100011 Beijing Dongcheng District, West Binhe Road, No. 22

Applicant after: CHINA ENERGY INVESTMENT Corp.,Ltd.

Applicant after: Beijing low carbon clean energy Research Institute

Address before: 100011 Beijing Dongcheng District, West Binhe Road, No. 22

Applicant before: CHINA ENERGY INVESTMENT Corp.,Ltd.

Applicant before: NATIONAL INSTITUTE OF CLEAN-AND-LOW-CARBON ENERGY

GR01 Patent grant
GR01 Patent grant