Composite molecular sieve of beta-configuration molecular sieve and MOR-configuration molecular sieve as well as preparation method and application of composite molecular sieve

Abstract

The invention relates to a preparation method of a beta-configuration molecular sieve and MOR-configuration molecular sieve composite microporous material with a double-microporous structure and application of the composite microporous material in light alkane isomerization. The preparation method of the composite molecular sieve comprises the following steps: providing a first molecular sieve containing a first template agent, and then preparing a second molecular sieve in the presence of a second template agent and the first molecular sieve containing the first template agent to obtain the composite molecular sieve, wherein the first template agent and the second template agent are different in chemical structure, and the first molecular sieve is a beta-configuration molecular sieve and the second molecular sieve is an MOR-configuration molecular sieve. The composite molecular sieve provided by the invention can effectively improve the selectivity of high-octane-number component multi-branched-chain alkane, thereby improving the product quality.

Description

Technical Field

[0001] This invention relates to a molecular sieve, and more specifically to a method for preparing a composite microporous material of a beta-configuration molecular sieve and a MOR-configuration molecular sieve with a dual microporous structure and its application in the isomerization of light alkane. Background Technology

[0002] With increasingly stringent environmental regulations and a faster pace of upgrades to gasoline quality standards, the demand for high-octane clean gasoline is growing daily. Light alkane isomerization technology, as one of the most economical and effective methods for producing high-octane clean gasoline, is attracting increasing attention.

[0003] Light alkane isomerization catalysts, as the core of isomerization technology, are crucial to its development. Currently, industrially applied light alkane isomerization catalysts mainly include low-temperature and medium-temperature catalysts. Low-temperature isomerization catalysts are primarily prepared by loading precious metals Pt or Pd onto halogen-containing alumina. These catalysts offer advantages such as low reaction temperature, high catalytic activity, small cracking reaction size, and high liquid-phase yield, and the technology is relatively mature. However, these catalysts are highly sensitive to impurities such as sulfur and water, and halogens are easily lost during production, requiring chlorine replenishment, and can also cause corrosion problems in the production equipment. Medium-temperature isomerization catalysts, on the other hand, have higher reaction temperatures, typically between 250°C and 300°C. Since isomerization is a slightly exothermic reaction, lower temperatures are more conducive to its progress. Medium-temperature isomerization catalysts mainly use molecular sieves loaded with precious or non-precious metals as the main component. These catalysts have advantages such as high resistance to impurities and strong tolerance, and are fully renewable and reusable, thus possessing greater value for industrial applications.

[0004] Chinese patent CN108993575A discloses a noble metal catalyst for the isomerization of n-alkanes supported on a ZSM-5 and SAPO-11 composite molecular sieve and cerium as a supporting structural aid, as well as its preparation method and application. This invention uses a composite molecular sieve support, which has suitable acid centers and acid strength distribution, thus improving the mass transfer efficiency between the catalyst and reactants.

[0005] Chinese patent CN105521811B discloses a hydrocarbon isomerization catalyst with two pore systems of different pore sizes, prepared using a macroporous pore-forming agent and small-grained mordenite. The mordenite pore structure provides a smaller pore system, while the pore-forming agent provides a macroporous pore system, thereby increasing the diffusion rate of reactants and products and avoiding deep reactions of the reactants.

[0006] Although the above molecular sieve-based alkane isomerization catalysts were designed and modified in terms of acidity and pore structure, which improved the reaction activity and suppressed the degree of side reactions to a certain extent, they failed to further optimize the distribution of the target product, especially the low content of multi-branched isomers of the high-octane component. Summary of the Invention

[0007] To address the shortcomings of existing technologies, this invention provides a method for preparing a composite microporous material of beta-configured molecular sieve and MOR-configured molecular sieve with a dual microporous structure. When applied to the isomerization reaction of light alkane, it results in a high yield of isomeric alkanes and significantly improves the selectivity of high-octane multi-branched alkanes.

[0008] The present invention relates in a first aspect to a method for manufacturing a composite molecular sieve, comprising the following steps: providing a first molecular sieve containing a first template agent (e.g., manufacturing the first molecular sieve containing the first template agent in the presence of the first template agent), and then manufacturing a second molecular sieve in the presence of a second template agent and the first molecular sieve containing the first template agent to obtain the composite molecular sieve, wherein the first template agent and the second template agent are chemically different, and the first molecular sieve is a beta-configured molecular sieve and the second molecular sieve is a MOR-configured molecular sieve.

[0009] The inventors of this invention have discovered that, in a preferred embodiment, by controlling the amount of MOR-configured molecular sieve, the MOR-configured molecular sieve can effectively cover the surface of the beta-configured molecular sieve without significantly hindering the entry of light n-alkanes into the pores of the beta-configured molecular sieve, thus keeping the pores effectively open. Furthermore, the pore structure of the outer MOR-configured molecular sieve prevents the generated monomethyl isomer from rapidly diffusing out of the beta-configured molecular sieve, thereby further generating a dimethyl isomer with a higher octane number and increasing the octane number of the product.

[0010] In a second aspect, the present invention relates to a composite molecular sieve, comprising a first molecular sieve and a second molecular sieve covering the surface of the first molecular sieve, wherein the first molecular sieve is a beta molecular sieve, the second molecular sieve is a MOR molecular sieve, and the mass ratio of the first molecular sieve to the second molecular sieve is (60-99):1, preferably (70-99):1, and more preferably (80-99):1.

[0011] In a third aspect, the present invention relates to a hydroisomerization catalyst comprising the composite molecular sieve and the active metal component of the present invention.

[0012] The present invention relates in a fourth aspect to a hydroisomerization method, comprising the step of subjecting a light n-alkane to a hydroisomerization reaction in the presence of the hydroisomerization catalyst of the present invention.

[0013] Technical effect

[0014] Compared with the prior art, the present invention has the following advantages:

[0015] This invention utilizes the amphiphilicity of a combined template agent to grow MOR molecular sieves on beta molecular sieves, and through the self-assembly of the template agent, forms a bimicroporous composite molecular sieve with two different pore sizes and interconnected "variable-diameter combined channels". The primary site of isomerization reactions is the beta molecular sieve, while the MOR molecular sieve provides local confinement, preventing the monomethyl branched isomers generated in the light alkane isomerization reaction within the beta molecular sieve from rapidly diffusing out of its channels. This allows for further isomerization, generating dimethyl branched isomers with higher octane numbers, thereby significantly improving product quality. Attached Figure Description

[0016] Figure 1 The images show the XRD patterns of the composite molecular sieve synthesized in Example 1.

[0017] Figure 2 These are the pore size distribution diagrams of the beta molecular sieve and the composite molecular sieve in Example 1 of this invention.

[0018] Figure 3 The results are TEM characterization results of the composite molecular sieve synthesized in Example 1 of this invention. Detailed Implementation

[0019] The specific embodiments of the present invention will be described in detail below. However, it should be noted that the scope of protection of the present invention is not limited to these specific embodiments, but is determined by the claims in the appendix.

[0020] All publications, patent applications, patents, and other references mentioned in this specification are incorporated herein by reference. Unless otherwise defined, all technical and scientific terms used in this specification have the meanings commonly understood by those skilled in the art. In case of conflict, the definitions in this specification shall prevail.

[0021] When this specification uses the prefixes “known to those skilled in the art,” “prior art,” or similar terms to derive materials, substances, methods, steps, apparatus, or components, the objects derived from such prefixes cover those commonly used in the art at the time of this application, but also include those that are not currently commonly used but will become generally recognized in the art as suitable for similar purposes.

[0022] In the context of this invention, all numerical values ​​of parameters (e.g., quantity or condition) should be understood to be modified by the term “about” in all cases, regardless of whether “about” actually appears before the numerical value.

[0023] In the context of this invention, "substantially" means that deviations that are acceptable or reasonable to those skilled in the art are permitted, such as deviations within ±2%, ±1%, ±0.5%, or ±0.1%.

[0024] In the context of this invention, the XRD spectrum measurement method is based on the following experimental conditions: Cu target, Kα radiation source, operating voltage 40kV, and tube current 80mA.

[0025] In the context of this invention, the method for measuring the composite structure formed by the first molecular sieve and the second molecular sieve is to use a JEM-2100 high-resolution transmission electron microscope from JEOL Corporation of Japan.

[0026] In the context of this invention, the type of the second molecular sieve is determined by XRD analysis of the powder obtained after lightly grinding the composite molecular sieve and sieving it. Specifically, the light grinding is performed by dry grinding using a mortar and pestle. To facilitate the detachment of the second molecular sieve from the surface of the carrier (first molecular sieve), the entire grinding process is conducted under relatively gentle conditions. The ground composite molecular sieve is then sieved through a mesh of 160 or finer, and the resulting powder (with a higher concentration of the second molecular sieve) is subjected to XRD analysis.

[0027] In the context of this invention, the pore size distribution is measured using an ASAP 2460 physical adsorption instrument via N2 adsorption-desorption method. Before measurement, the sample is activated by vacuuming at 300°C for 4 hours, and the pore size distribution is analyzed using a DFT model.

[0028] In the context of this invention, the average particle size is measured according to GB / T 6288-2021 Method for Determination of Particle Size of Granular Molecular Sieve.

[0029] In the context of this invention, the specific surface area, pore volume, and pore size are measured using an ASAP 2460 physical adsorption instrument via N2 adsorption-desorption method. Before measurement, the sample is activated by vacuuming at 300°C for 4 hours. The specific surface area of ​​the sample is calculated using the BET method, the pore volume is calculated using the BJH model, and the pore size distribution is analyzed using the DFT model.

[0030] In the context of this invention, the template agent content is measured by thermogravimetric analysis, and the weight loss at a temperature above 200°C until the weight loss curve stabilizes is taken as the template agent content of the molecular sieve.

[0031] In the context of this invention, the free water content is measured using a halogen moisture analyzer at a test temperature of 120°C for 10 minutes.

[0032] In the context of this invention, the method for measuring the template agent loss rate is as follows: the method is to measure by thermogravimetric analysis, and the weight loss at 200°C or above until the weight loss curve stabilizes is the template agent content. The template agent loss rate is calculated as: (template agent content in the molecular sieve before washing - template agent content in the molecular sieve after washing) / template agent content in the molecular sieve before washing * 100%.

[0033] Unless otherwise specified, all percentages, parts, ratios, etc. mentioned in this instruction manual are based on weight, and the pressure is gauge pressure.

[0034] In the context of this invention, any two or more embodiments or aspects of this invention can be arbitrarily combined, and the resulting technical solutions are part of the original disclosure of this specification and also fall within the protection scope of this invention.

[0035] According to one embodiment of the present invention, a method for manufacturing a composite molecular sieve includes the following steps:

[0036] 1) Provide a first molecular sieve containing a first template agent (e.g., manufacture the first molecular sieve containing the first template agent in the presence of the first template agent), then,

[0037] 2) A second molecular sieve is manufactured in the presence of a second template agent and a first molecular sieve containing a first template agent to obtain the composite molecular sieve.

[0038] According to the present invention, "then" means that step 2) must be performed after step 1). Specifically, the second molecular sieve is manufactured only after the first molecular sieve containing the first template agent is manufactured according to step 1). Therefore, according to the present invention, the first molecular sieve containing the first template agent and the second molecular sieve are not manufactured simultaneously. As a case of simultaneous manufacturing, for example, the first molecular sieve and the second molecular sieve can be manufactured simultaneously in the presence of the first template agent and the second template agent.

[0039] According to one embodiment of the present invention, the first molecular sieve is a beta-configured molecular sieve, and the second molecular sieve is a MOR-configured molecular sieve. The inventors of the present invention have discovered that, in a preferred embodiment, the beta molecular sieve can provide a suitable reaction site for the isomerization reaction of light alkane, while the MOR-configured molecular sieve has a smaller average pore size than the beta molecular sieve and can provide a local confinement function, preventing the monomethyl branched isomers generated in the isomerization reaction of light alkane occurring in the beta molecular sieve from rapidly diffusing out of its pores, thus allowing further isomerization to generate polymethyl branched isomers with higher octane numbers.

[0040] According to one embodiment of the present invention, in step 1), a silicon source, an aluminum source, an alkali source, and water are also present, wherein the silicon source (calculated as SiO2): the aluminum source (calculated as Al2O3): the alkali source (calculated as OH-) -1 The molar ratio of water to the first template agent is 1:0.01-0.05:0.01-0.5:5-25:0.05-0.6, preferably 1:0.012-0.04:0.02-0.4:7.5-20:0.1-0.5.

[0041] According to one embodiment of the present invention, in step 2), a silicon source, an aluminum source, an alkali source, and water are also present, wherein the silicon source (calculated as SiO2): the aluminum source (calculated as Al2O3): the alkali source (calculated as OH-) -1 The molar ratio of water to the second template agent is 1:0.0167-0.125:0.01-0.8:5-60:0.02-0.8, preferably 1:0.02-0.1:0.06-0.6:10-50:0.05-0.6.

[0042] According to one embodiment of the present invention, the mass ratio of the first molecular sieve containing the first template agent to the silicon source (in SiO2) in step 2) is (59-99):1, preferably (69-99):1, and more preferably (79-99):1.

[0043] According to one embodiment of the present invention, the average particle size of the first molecular sieve containing the first template agent is 85% or more passing through 60 mesh, preferably 90% or more passing through 100 mesh. The inventors of the present invention have found that a suitable molecular sieve particle size is beneficial for the growth of a second molecular sieve on its surface; when the particle size is too large, it leads to a decrease in specific surface area, a reduction in the number of pores, an increase in free diffusion paths, and a decrease in catalytic activity.

[0044] According to one embodiment of the present invention, the free water content of the first molecular sieve containing the first template agent is no more than 10 wt%, preferably no more than 5 wt%. The inventors of the present invention have found that a lower water content can ensure the particle dispersion of the first molecular sieve. If the water content is too high, it will cause the dispersibility of the first molecular sieve to decrease, resulting in a viscous state, which will affect the growth of the second molecular sieve on its surface.

[0045] According to one embodiment of the present invention, based on a total weight of 100wt% of the first molecular sieve containing the first template agent, the content of the first template agent is 5wt%-48wt%, preferably 7wt%-40wt%.

[0046] According to one embodiment of the present invention, after the first molecular sieve containing the first template agent is washed twice with deionized water at room temperature, the loss rate of the first template agent is less than 10 wt% (preferably less than 5 wt% or less than 2 wt%). According to the present invention, the first template agent is substantially entirely embedded within the pores of the first molecular sieve during its manufacturing process, and the interaction between the first molecular sieve and the template agent is not simply physical adsorption or physical mixing; therefore, the washing loss rate is very small.

[0047] According to the present invention, the first template agent and the second template agent are chemically different. Preferably, the first template agent and the second template agent have similar polarities and can form hydrogen bonds with each other in the presence of water. The similar polarities of the first and second template agents attract them to each other, and both template agents contain nitrogen-containing functional groups, which then bond with each other through hydrogen bonds formed by these nitrogen-containing functional groups.

[0048] According to the present invention, "similar polarity" means that the first template agent and the second template agent have a small difference in molecular polarity. Specifically, if the two template agent molecules contain the same type and similar number of polar functional groups and the polar functional groups are relatively symmetrically positioned in the molecules, especially ammonium groups or substituted ammonium groups, or if the two template agents are mutually soluble or have a small difference in solubility in the same solvent (e.g., less than 20%), then they can be considered to have a small difference in molecular polarity.

[0049] The inventors of this invention have discovered that the first template agent and the second template agent have similar polarities, which attracts them to each other. Furthermore, if both template agents contain nitrogen-containing functional groups, the two template agents can bond with each other after forming hydrogen bonds through the nitrogen-containing functional groups.

[0050] According to one embodiment of the present invention, the first template agent can be used to synthesize the first molecular sieve. Specifically, the first template agent is selected from at least one of tetraethylammonium hydroxide, tetraethylammonium fluoride, triethylamine, tetrapropylammonium hydroxide, tetraethylammonium chloride, tetraethylammonium bromide, and tetraethylammonium iodide, preferably tetraethylammonium hydroxide.

[0051] According to one embodiment of the present invention, the second template agent can be used to synthesize the second molecular sieve. Specifically, the second template agent is selected from at least one of benzyltrimethylamine, tetraethylammonium bromide, tributylamine, triethylamine, diisopropylamine, isobutylamine, diisobutylamine, tert-octylamine, neopentylamine, cyclohexylamine, cycloheptylamine, 1,2-diaminocyclohexane, 2- or 4-methylcyclohexylamine, tetramethylethyldiamine, and hexamethyleneimine, preferably hexamethyleneimine.

[0052] According to one embodiment of the present invention, step 1) includes the following steps:

[0053] 1-1) A first mixture is formed by mixing a silicon source, an aluminum source, an alkali source, a first template agent, and water.

[0054] 1-2) Crystallize the first mixture to generate the first molecular sieve containing the first template agent.

[0055] 1-3) Separate the first molecular sieve containing the first template agent (preferably, after optional washing and / or optional filtration, dry (especially spray dry) the first molecular sieve containing the first template agent).

[0056] According to one embodiment of the present invention, in step 1-2), the crystallization conditions include: crystallization pressure from atmospheric pressure to system autogenous pressure, presence or absence of seed crystals, crystallization temperature of 100℃-200℃ (preferably 120℃-180℃), and crystallization time of 20h-150h (preferably 24h-80h).

[0057] According to one embodiment of the present invention, in steps 1-3), the drying conditions include: a drying temperature of 60℃-250℃ (preferably 80℃-200℃) and a drying time of 0.1h-20h (preferably 4h-12h).

[0058] According to one embodiment of the present invention, in steps 1-3), the conditions for spray drying include: solid content 35%-65%, inlet air temperature 150℃-250℃, outlet air temperature 80℃-150℃, and air velocity 300m / s. 3 / h-1500m 3 / h.

[0059] According to one embodiment of the present invention, after steps 1-3), the first molecular sieve containing the first template agent is further pulverized (e.g., ground) to an average particle size of 85% or more passing through 60 mesh (preferably 90% or more passing through 100 mesh).

[0060] According to a preferred embodiment of the present invention, the first molecular sieve containing the first template agent is substantially not removed after manufacturing. More preferably, the manufacturing method of the present invention does not include a step capable of removing part or all of the first template agent from the first molecular sieve containing the first template agent. The inventors of the present invention have discovered that if the first molecular sieve does not contain a template agent, or if a first molecular sieve without a template agent is added during the synthesis of the second molecular sieve, and both the first and second template agents are added simultaneously, this situation leads to the inability to form a continuous pore structure between the first and second molecular sieves during the synthesis of the composite molecular sieve, severely restricting the diffusion of reactants and products, and causing side reactions such as pyrolysis. Since calcination can remove the template agent, according to a preferred embodiment of the present invention, step 1) does not include a calcination step.

[0061] According to one embodiment of the present invention, step 2) includes the following steps:

[0062] 2-1) A second mixture is formed by mixing a silicon source, an aluminum source, an alkali source, a second template agent, and water.

[0063] 2-2) Mix the first molecular sieve containing the first template agent with the second mixture to obtain a composite mixture.

[0064] 2-3) Optionally, after drying the composite mixture, crystallize the composite mixture to generate the composite molecular sieve.

[0065] 2-4) After optional washing and / or optional filtration, the composite molecular sieve is dried.

[0066] According to one embodiment of the present invention, there is no particular limitation on the silicon source, which can be any silicon source conventionally used in the manufacture of molecular sieves in the art, such as one or more of silica sol, fumed silica, water glass and organosilicone esters, preferably silica sol.

[0067] According to one embodiment of the present invention, there is no particular limitation on the aluminum source, which can be any aluminum source conventionally used in the manufacture of molecular sieves in the art. Specifically, one or more of aluminum hydroxide, boehmite, aluminum isopropoxide, sodium aluminate, aluminum sulfate and aluminum chloride can be cited, with aluminum hydroxide being preferred.

[0068] According to one embodiment of the present invention, there is no particular limitation on the alkali source, which can be any alkali source conventionally used in the manufacture of molecular sieves in the art, such as sodium hydroxide or potassium hydroxide, preferably sodium hydroxide.

[0069] According to one embodiment of the present invention, in step 2-2), the second mixture is coated (e.g., sprayed) onto the first molecular sieve containing the first template agent in a finely granulated form.

[0070] According to one embodiment of the present invention, in step 2-2), the morphological integrity (particularly the bulk structure or pore structure) of the first molecular sieve containing the first template agent is substantially maintained after the mixing.

[0071] According to one embodiment of the present invention, in steps 2-3), drying is an optional step, but drying is preferred. The inventors of the present invention have discovered that the drying process allows the second molecular sieve precursor to form a dry gel on the surface of the first molecular sieve, which is more conducive to the growth of the molecular sieve on its surface in the subsequent crystallization process.

[0072] According to one embodiment of the present invention, in step 2-3), the composite mixture is dried, and the crystallization conditions include: crystallization pressure from atmospheric pressure to system autogenous pressure, water vapor concentration of 20%-70% (preferably 30%-50%), crystallization temperature of 120℃-200℃ (preferably 140℃-180℃), and crystallization time of 24h-150h (preferably 30h-130h).

[0073] According to one embodiment of the present invention, in steps 2-3), the composite mixture is not dried, and the crystallization conditions include: crystallization pressure from atmospheric pressure to system autogenous pressure, crystallization temperature of 120℃-200℃ (preferably 150℃-180℃), and crystallization time of 18h-150h (preferably 24h-120h).

[0074] According to one embodiment of the present invention, in step 2-3), the drying conditions include: a drying temperature of 60℃-250℃ (preferably 80℃-200℃) and a drying time of 0.1h-20h (preferably 4h-12h).

[0075] According to one embodiment of the present invention, in steps 2-4), the drying conditions include: a drying temperature of 60℃-180℃ (preferably 80℃-150℃) and a drying time of 2h-20h (preferably 4h-12h).

[0076] According to one embodiment of the present invention, the manufacturing method further includes a step of calcining the composite molecular sieve after steps 2-4), wherein the calcination conditions include: calcination temperature of 400℃-650℃ (preferably 450℃-600℃) under an oxygen-containing atmosphere, and calcination time of 3h-18h (preferably 4h-12h).

[0077] According to one embodiment of the present invention, in step 1), the first molecular sieve containing the first template agent is substantially not removed after manufacturing.

[0078] According to one embodiment of the present invention, in step 2), the morphological integrity (particularly the bulk structure or pore structure) of the first molecular sieve containing the first template agent is substantially maintained after the mixing. In other words, the morphological integrity (particularly the bulk structure or pore structure) of the first molecular sieve containing the first template agent is substantially maintained under the manufacturing conditions of the second molecular sieve. Therefore, according to the present invention, the second molecular sieve is grown in situ on the first molecular sieve containing the first template agent. The inventors of the present invention have found that maintaining the morphological integrity of the first molecular sieve is beneficial to the connectivity of the pore structure of the composite molecular sieve and also provides suitable active sites and reaction sites for the isomerization reaction of light alkane. If the morphological integrity of the first molecular sieve is severely damaged, the second molecular sieve will be unable to grow on its surface, affecting the connectivity of the pore structure and severely impacting the confinement effect.

[0079] According to one embodiment of the present invention, a composite molecular sieve is also provided, comprising a first molecular sieve and a second molecular sieve. According to the present invention, the composite molecular sieve can be manufactured according to the manufacturing method described above.

[0080] In the composite molecular sieve of the present invention, the first molecular sieve has a complete, smooth crystal structure, at least a portion of its surface is covered by a dense layer of the second molecular sieve, and preferably, the second molecular sieve densely covers substantially the entire surface of the first molecular sieve.

[0081] According to one embodiment of the present invention, the mass ratio of the first molecular sieve to the second molecular sieve is (60-99):1, preferably (70-99):1, and more preferably (80-99):1. The inventors of this invention have discovered that the composite molecular sieve formed by this invention mainly consists of the second molecular sieve grown on the surface of the first molecular sieve. If the content of the second molecular sieve is too high, it will cover part of the pore structure of the first molecular sieve, affecting the mass transfer process of the reactants and products, and increasing the chance of pyrolysis reactions.

[0082] According to one embodiment of the present invention, the average particle size of the first molecular sieve is 85% or more passing through 60 mesh (preferably 90% or more passing through 100 mesh).

[0083] According to the present invention, since the second molecular sieve accounts for a lower proportion in the entire composite molecular sieve, its contribution to the XRD pattern is smaller. Therefore, the XRD pattern of the composite molecular sieve is substantially the same as that of the first molecular sieve. If the relative intensity of the strongest characteristic diffraction peak in the XRD pattern is designated as 100, then vw = very weak (>0 to <10); w = weak (10 to ≤20); m = moderate (>20 to ≤40); s = strong (>40 to ≤60); vs = very strong (>60 to ≤100). Here, "substantially the same" means that the composite molecular sieve is consistent with the first molecular sieve at least on all characteristic diffraction peaks with relative intensities of s to vs (preferably m to vs). In other words, the composite molecular sieve substantially does not show characteristic diffraction peaks with relative intensities of s to vs associated with the second molecular sieve (when the second molecular sieve is measured alone), unless such characteristic diffraction peaks are shared by both the first and second molecular sieves. Based on the surface properties described above in this specification, and without any theoretical limitations, the inventors of this invention believe that the composite molecular sieve of this invention substantially exhibits the characteristics of the first molecular sieve in terms of bulk properties and substantially exhibits the characteristics of the second molecular sieve in terms of surface properties.

[0084] According to the present invention, the first molecular sieve and the composite molecular sieve have two distribution peaks in the micropore size distribution range: small pore size and large pore size. However, there is a significant difference in the number of pores between the two. Compared with the first molecular sieve, the number of large pores in the composite molecular sieve is reduced, while the number of small pores is increased. This is because after the second molecular sieve with a smaller pore size is assembled onto the first molecular sieve, it covers part of the large pores on the surface of the first molecular sieve, thereby reducing the number of large pores. However, the reduction is small, resulting in the first molecular sieve and the second molecular sieve having essentially interconnected pores.

[0085] According to one embodiment of the present invention, the composite molecular sieve has a bimodal pore distribution.

[0086] According to one embodiment of the present invention, the most probable pore sizes of the composite molecular sieve are 0.67 nm-0.72 nm (preferably about 0.69 nm) and 0.61 nm-0.66 nm (preferably about 0.64 nm), respectively. The channels with the most probable pore size of 0.67 nm-0.72 nm account for more than 80% (preferably about 90%) of the total pore volume, and the BET specific surface area is 200 m². 2 / g-650m 2 / g (preferably 250m) 2 / g-600m 2 / g), with a pore volume of 0.15ml / g-0.60ml / g (preferably 0.22ml / g-0.55ml / g).

[0087] According to one embodiment of the present invention, a hydroisomerization catalyst (preferably a low-carbon alkane hydroisomerization catalyst) is also involved, comprising the composite molecular sieve and active metal component as described above.

[0088] According to one embodiment of the present invention, based on 100 wt% of the total weight of the hydroisomerization catalyst, the content (dry basis) of the composite molecular sieve is 1 wt%-80 wt% (preferably 10 wt%-70 wt%, more preferably 20 wt%-60 wt%). Additionally, the content (based on metal element) of the active metal component is 0.01 wt%-10 wt% (preferably 0.05 wt%-8.0 wt%, more preferably 0.1 wt%-5.0 wt%).

[0089] According to one embodiment of the present invention, the active metal component is selected from at least one noble metal element of Group VIII of the periodic table, preferably at least one of Pt and Pd, especially Pt.

[0090] According to one embodiment of the present invention, a hydroisomerization method is also involved, comprising the step of carrying out a hydroisomerization reaction of a light alkane in the presence of a hydroisomerization catalyst as described above.

[0091] According to one embodiment of the present invention, the conditions for the hydroisomerization reaction include: a reaction temperature of 200°C-350°C, a reaction pressure of 1 MPa-10 MPa, and a volume hourly space velocity of 0.5 h⁻¹. -1 -4.0h -1 .

[0092] According to one embodiment of the present invention, a molecular sieve precursor is also provided, comprising a molecular sieve and a template agent. The precursor has an average particle size of at least 80% passing through 60 mesh (preferably at least 90% passing through 100 mesh), a free water content of no more than 10% (preferably no more than 5%), and the molecular sieve is a beta-configured molecular sieve.

[0093] According to one embodiment of the present invention, the template agent is selected from at least one of tetraethylammonium hydroxide, tetraethylammonium fluoride, triethylamine, tetrapropylammonium hydroxide, tetraethylammonium chloride, tetraethylammonium bromide, tetraethylammonium iodide, triethanolamine, polyvinyl alcohol, and sodium carboxymethyl cellulose, preferably tetraethylammonium hydroxide.

[0094] According to one embodiment of the present invention, after the precursor is washed twice with deionized water at room temperature, the loss rate of the template agent is less than 10 wt% (preferably less than 5 wt% or less than 2 wt%).

[0095] According to one embodiment of the present invention, the content of the template agent is 5wt%-46wt% (preferably 7wt%-38wt%), based on a total weight of 100wt% of the precursor.

[0096] Example

[0097] The present invention will be further described in detail below with reference to examples and comparative examples, but the present invention is not limited to these examples.

[0098] In the following examples and comparative examples, the performance evaluation of the catalyst isomerization reaction was carried out using n-hexane as a model compound. The catalyst was pre-reduced before feeding to convert the noble metal on the catalyst into a reduced state. The reduction conditions were as follows: in the presence of hydrogen, at a temperature of 400°C, a pressure of 2 MPa, and a time of 4 hours. The evaluation reaction conditions were as follows: in the presence of hydrogen, at a temperature of 200°C-350°C and a pressure of 2 MPa.

[0099] Example 1

[0100] (1) Mix 2g sodium hydroxide, 2.34g aluminum hydroxide, 58.90g tetraethylammonium hydroxide (35wt%), 100g silica sol (30wt%) and 27g water evenly. After aging at room temperature for 2 hours, load the mixture into a crystallization kettle and heat it to 175℃ for dynamic hydrothermal crystallization for 36 hours. After crystallization, spray dry the crystallized product under the following conditions: solid content 38%, inlet air temperature 170℃, outlet air temperature 90℃, and inlet air volume 480m³. 3 / h, yielding the main molecular sieve N1, which is a beta molecular sieve.

[0101] The main molecular sieve N1 is not calcined, and its average particle size is more than 95% passing through 100 mesh, free water content is 3.9 wt%, template agent content is 12 wt%, and template agent loss rate is less than 4.2 wt%.

[0102] (2) Mix 0.19g hexamethyleneimine, 0.12g sodium hydroxide, 3.92g silica sol (30wt%), 0.129g sodium aluminate and 6.43g water evenly, then spray it onto the main molecular sieve N1. After drying at 90℃ for 2h, a composite molecular sieve dry gel is obtained. Then, it is crystallized at 170℃ for 72h under the action of water vapor, dried at 90℃ for 8h, and calcined at 550℃ for 4h to obtain a double microporous composite molecular sieve M1, which is a composite molecular sieve formed by coating beta molecular sieve with MOR molecular sieve.

[0103] Figure 1The XRD characterization results show that composite molecular sieve 1 is the composite molecular sieve prepared in this invention, and composite molecular sieve 2 is the composite molecular sieve after light grinding. Both mainly exhibit the characteristic diffraction peaks of beta molecular sieves. The composite molecular sieve is identical to the first molecular sieve (beta) in all characteristic diffraction peaks with relative intensities from w to vs.

[0104] Figure 2 The results show the pore size distribution of the first molecular sieve and the composite molecular sieve. It can be seen that the composite molecular sieve has two distribution peaks: small pore size and large pore size. However, there is a significant difference in the number of pores between the two. Compared with the first molecular sieve, the increase in the number of small pores indicates the introduction of the second molecular sieve. In contrast, the number of large pores in the composite molecular sieve decreases, but the decrease is small, indicating that the pores of the first and second molecular sieves are basically interconnected.

[0105] TEM images revealed that the dual-microporous composite molecular sieve M1 comprises a first molecular sieve (beta molecular sieve) and a second molecular sieve (MOR molecular sieve) covering the surface of the first molecular sieve, such as... Figure 3 As shown. According to Figure 3 It can be seen that a dense crystalline material covers the original crystal surface of the first molecular sieve beta, and there is a clear boundary between the two.

[0106] Measurements showed that the mass ratio of the first to the second molecular sieve in the dual-microporous composite molecular sieve M1 was 87:1. The channels of the first and second molecular sieves were essentially interconnected, and the XRD pattern of the composite molecular sieve was substantially the same as that of the first molecular sieve. The composite molecular sieve exhibited a bimodal pore distribution, with the most probable pore diameters being 0.69 nm and 0.64 nm, respectively. The most probable pore diameter of 0.69 nm accounted for 95% of the total pore volume. The BET specific surface area of ​​the composite molecular sieve was 489 m². 2 / g, pore volume is 0.45ml / g.

[0107] (3) Take 80g of the prepared dual-microporous composite molecular sieve M1 (dry basis, the same below) and 20g of pseudoboehmite (dry basis) and mix them thoroughly. Add 1.5mL of concentrated nitric acid (mass fraction of 65%) and an appropriate amount of water, knead thoroughly, and then extrude into strips. Then, impregnate the noble metal Pt by the impregnation method. The Pt loading is 0.45wt% of the support. After drying at 80℃ for 8h and calcining at 450℃ for 6h, the catalyst S1 of this invention is obtained. The evaluation results of the catalyst are shown in Table 1.

[0108] Example 2

[0109] The synthesis of the composite molecular sieve and the preparation of the catalyst are the same as in Example 1, except that: the SiO2 / Al2O3 ratio of the beta molecular sieve is 25, the mass ratio of the first molecular sieve to the second molecular sieve is 99:1, and the dual-microporous composite molecular sieve has a composite structure similar to that in Example 1. The catalyst was named S2, and the evaluation results are shown in Table 1.

[0110] Example 3

[0111] The synthesis of the composite molecular sieve and the preparation of the catalyst are the same as in Example 1, except that the mass ratio of the first molecular sieve to the second molecular sieve is 81:1, and the dual-microporous composite molecular sieve has a composite structure similar to that in Example 1. The catalyst was named S3, and the evaluation results are shown in Table 1.

[0112] Example 4

[0113] The synthesis of the composite molecular sieve and the preparation of the catalyst are the same as in Example 1, except that the mass ratio of the first molecular sieve containing the first template agent to the silicon source (calculated as SiO2) added during the synthesis of the second molecular sieve is 65:1. The dual-microporous composite molecular sieve has a composite structure similar to that in Example 1. The catalyst was named S4, and the evaluation results are shown in Table 1.

[0114] Example 5

[0115] The synthesis of the composite molecular sieve and the preparation of the catalyst are the same as in Example 1, except that the mass ratio of the first molecular sieve containing the first template agent to the silicon source (calculated as SiO2) added during the synthesis of the second molecular sieve is 115:1. The dual-microporous composite molecular sieve has a composite structure similar to that in Example 1. The catalyst is named S5, and the evaluation results are shown in Table 1.

[0116] Example 6

[0117] The synthesis of the composite molecular sieve and the preparation of the catalyst are the same as in Example 1, except that: the average particle size of the first molecular sieve containing the first template agent is 70% passing through 60 mesh, and the dual-microporous composite molecular sieve has a composite structure similar to that in Example 1. The catalyst was named S6, and the evaluation results are shown in Table 1.

[0118] Example 7

[0119] The synthesis of the composite molecular sieve and the preparation of the catalyst are the same as in Example 1, except that the free water content of the first molecular sieve containing the first template agent is 25 wt%, and the dual-microporous composite molecular sieve has a composite structure similar to that in Example 1. The catalyst was named S7, and the evaluation results are shown in Table 1.

[0120] Example 8

[0121] The synthesis of the composite molecular sieve and the preparation of the catalyst were the same as in Example 1, except that: after the first molecular sieve was crystallized, the product was subjected to ordinary drying at a temperature of 100°C for 4 hours. The resulting dual-microporous composite molecular sieve had a composite structure similar to that in Example 1. The catalyst was named S8, and the evaluation results are shown in Table 1.

[0122] Example 9

[0123] The synthesis of the composite molecular sieve and the preparation of the catalyst are the same as in Example 1, except that: the amount of sodium hydroxide added to the raw material for synthesizing the second molecular sieve is 0.62g, which dissolves and destroys part of the first molecular sieve. The resulting dual-microporous composite molecular sieve has a composite structure similar to that in Example 1. The catalyst is named S9, and the evaluation results are shown in Table 1.

[0124] Example 10

[0125] The synthesis of the composite molecular sieve and the preparation of the catalyst are the same as in Example 1, except that no water vapor participates in the reaction during the crystallization of the second molecular sieve, and the dual-microporous composite molecular sieve has a composite structure similar to that in Example 1. The catalyst was named S10, and the evaluation results are shown in Table 1.

[0126] Comparative Example 1

[0127] The synthesis of the composite molecular sieve and the preparation and evaluation of the catalyst were the same as in Example 1, except that the first molecular sieve was a beta molecular sieve that had been calcined and had its template agent removed. The catalyst was named D1, and the evaluation results are shown in Table 1.

[0128] Comparative Example 2

[0129] The synthesis of the composite molecular sieve and the preparation and evaluation of the catalyst were the same as in Example 1, except that 4.96 g of hexamethyleneimine was added to the raw material for synthesizing the first molecular sieve, crystallized at 175 °C for 72 h, and then washed, dried, and calcined to obtain the composite molecular sieve. The catalyst was named D2, and the evaluation results are shown in Table 1.

[0130] Comparative Example 3

[0131] The synthesis of the composite molecular sieve, as well as the preparation and evaluation of the catalyst, were the same as in Example 1, except that: the first molecular sieve was used to synthesize a MOR molecular sieve, and the second molecular sieve was used to synthesize a beta molecular sieve. The resulting composite molecular sieve was formed by coating the surface of the MOR molecular sieve with a beta molecular sieve. The catalyst was named D3, and the evaluation results are shown in Table 1.

[0132] Comparative Example 4

[0133] The synthesis of the composite molecular sieve and the preparation and evaluation of the catalyst were the same as in Example 1, except that the first molecular sieve was calcined after drying at a temperature of 340°C for 4 hours. The catalyst was named D4, and the evaluation results are shown in Table 1.

[0134] Comparative Example 5

[0135] The synthesis of the composite molecular sieve and the preparation and evaluation of the catalyst were the same as in Example 1, except that: the second molecular sieve, MOR molecular sieve, was synthesized first, and then coated onto the first molecular sieve at a mass ratio of 1:83. The catalyst was designated D5, and the evaluation results are shown in Table 1.

[0136] Table 1 Results of the hydroisomerization reaction of n-hexane over a catalyst

[0137] catalyst Reaction temperature / ℃ hexane conversion rate / % Dimethylbutane selectivity / % S1 280 81.1 34.5 S2 279 81.5 33.2 S3 278 80.6 33.6 S4 276 82.1 30.4 S5 282 80.9 31.3 S6 283 80.4 31.8 S7 281 81.0 30.2 S8 280 80.7 32.4 S9 277 81.4 29.6 S10 280 80.8 31.5 D1 283 81.4 23.8 D2 280 80.8 22.5 D3 274 80.3 25.5 D4 278 80.6 25.8 D5 280 81.0 24.6

Claims

1. A method for manufacturing a composite molecular sieve, comprising the following steps: 1) Provide a first molecular sieve containing a first template agent (e.g., manufacture the first molecular sieve containing the first template agent in the presence of the first template agent), then 2) A second molecular sieve is manufactured in the presence of a second template agent and the first molecular sieve containing the first template agent to obtain the composite molecular sieve. The first template agent and the second template agent are different in chemical structure, and the first molecular sieve is a beta molecular sieve and the second molecular sieve is a MOR molecular sieve.

2. The manufacturing method according to claim 1, wherein in step 1), a silicon source, an aluminum source, an alkali source, and water are further present, wherein the silicon source (calculated as SiO2): the aluminum source (calculated as Al2O3): the alkali source (calculated as OH-) -1 The molar ratio of water to the first template agent is 1:0.01-0.05:0.01-0.5:5-25:0.05-0.6, preferably 1:0.012-0.04:0.02-0.4:7.5-20:0.1-0.5; and / or, in step 2), a silicon source, an aluminum source, an alkali source, and water are also present, wherein the silicon source (as SiO2): the aluminum source (as Al2O3): the alkali source (as OH) -1 The molar ratio of water to the second template agent is 1:0.0167-0.125:0.01-0.8:5-60:0.02-0.8, preferably 1:0.02-0.1:0.06-0.6:10-50:0.05-0.6; and / or, the mass ratio of the first molecular sieve containing the first template agent to the silicon source (based on SiO2) in step 2) is (59-99):1, preferably (69-99):1, more preferably (79-99):1; and / or, the average particle size of the first molecular sieve containing the first template agent is 85% or more passing through. The first molecular sieve containing the first template agent has a free water content of no more than 10 wt%, preferably no more than 5 wt%, and / or, based on the total weight of the first molecular sieve containing the first template agent as 100 wt%, the content of the first template agent is 5 wt%-48 wt%, preferably 7 wt%-40 wt%, and / or, after washing the first molecular sieve containing the first template agent twice with deionized water at room temperature, the loss rate of the first template agent is less than 10 wt% (preferably less than 5 wt% or less than 2 wt%).

3. The manufacturing method of claim 1, wherein the first template agent and the second template agent have similar polarity and are able to form hydrogen bonds with each other in the presence of water, and / or the first template agent can be used to synthesize the first molecular sieve, and / or the first template agent is selected from at least one of tetraethylammonium hydroxide, tetraethylammonium fluoride, triethylamine, tetrapropylammonium hydroxide, tetraethylammonium chloride, tetraethylammonium bromide, and tetraethylammonium iodide, preferably tetraethylammonium hydroxide, and / or the second template agent can be used to synthesize the second molecular sieve, and / or the second template agent is selected from at least one of benzyltrimethylamine, tetraethylammonium bromide, tributylamine, triethylamine, diisopropylamine, isobutylamine, diisobutylamine, tert-octylamine, neopentylamine, cyclohexylamine, cycloheptylamine, 1,2-diaminocyclohexane, 2- or 4-methylcyclohexylamine, tetramethylethyldiamine, and hexamethyleneimine, preferably hexamethyleneimine.

4. The manufacturing method of claim 1, wherein step 1) comprises the following steps: 1-1) A first mixture is formed by mixing a silicon source, an aluminum source, an alkali source, a first template agent, and water. 1-2) Crystallize the first mixture to generate the first molecular sieve containing the first template agent. 1-3) Separate the first molecular sieve containing the first template agent (preferably, after optional washing and / or optional filtration, dry (especially spray dry) the first molecular sieve containing the first template agent).

5. The manufacturing method of claim 4, wherein in steps 1-2), the crystallization conditions include: The crystallization pressure is from atmospheric pressure to the system's autogenous pressure, with or without seed crystals; the crystallization temperature is 100℃-200℃ (preferably 120℃-180℃); the crystallization time is 20h-150h (preferably 24h-80h); and / or, in steps 1-3), the drying conditions include: a drying temperature of 60℃-250℃ (preferably 80℃-200℃); a drying time of 0.1h-20h (preferably 4h-12h); and / or, in steps 1-3), the spray drying conditions include: a solid content of 35%-65%; an inlet air temperature of 150℃-250℃; an outlet air temperature of 80℃-150℃; and a wind speed of 300m / s. 3 / h-1500m 3 / h, and / or, further comprising, after steps 1-3), pulverizing (e.g., grinding) the first molecular sieve containing the first template agent to an average particle size of more than 85% passing through 60 mesh (preferably more than 90% passing through 100 mesh).

6. The manufacturing method of claim 1, excluding the step of removing part or all of the first template agent from the first molecular sieve containing the first template agent, and / or, wherein step 1) does not include a calcination step.

7. The manufacturing method of claim 1, wherein step 2) comprises the following steps: 2-1) A second mixture is formed by mixing a silicon source, an aluminum source, an alkali source, a second template agent, and water. 2-2) The first molecular sieve containing the first template agent is mixed with the second mixture to obtain a composite mixture. 2-3) Optionally, after drying the composite mixture, crystallize the composite mixture to generate the composite molecular sieve. 2-4) After optional washing and / or optional filtration, the composite molecular sieve is dried.

8. The manufacturing method of claim 7, wherein in step 2-2), the second mixture is finely coated (e.g., sprayed) onto the first molecular sieve containing the first template agent, and / or, in step 2-2), the morphological integrity (particularly the bulk structure or pore structure) of the first molecular sieve containing the first template agent is substantially maintained after the mixing.

9. The manufacturing method of claim 7, wherein in steps 2-3), the composite mixture is dried, and the crystallization conditions include: The crystallization pressure is from atmospheric pressure to the system's autogenous pressure, the water vapor concentration is 20%-70% (preferably 30%-50%), the crystallization temperature is 120℃-200℃ (preferably 140℃-180℃), the crystallization time is 24h-150h (preferably 30h-130h), and / or, in steps 2-3), the composite mixture is not dried, and the crystallization conditions include: a crystallization pressure from atmospheric pressure to the system's autogenous pressure, and a crystallization temperature of 120℃-200℃ (preferably 150℃-180℃). The crystallization time is 18h-150h (preferably 24h-120h), and / or, in step 2-3), the drying conditions include: a drying temperature of 60℃-250℃ (preferably 80℃-200℃) and a drying time of 0.1h-20h (preferably 4h-12h), and / or, in step 2-4), the drying conditions include: a drying temperature of 60℃-180℃ (preferably 80℃-150℃) and a drying time of 2h-20h (preferably 4h-12h).

10. The manufacturing method of claim 7, further comprising, after steps 2-4), a step of calcining the composite molecular sieve, wherein the calcination conditions include: Under an oxygen-containing atmosphere, the calcination temperature is 400℃-650℃ (preferably 450℃-600℃), and the calcination time is 3h-18h (preferably 4h-12h).

11. The manufacturing method of claim 1, wherein in step 1), the first molecular sieve containing the first template agent is substantially not removed after manufacturing, and / or, in step 2), the morphological integrity (particularly the bulk structure or pore structure) of the first molecular sieve containing the first template agent is substantially maintained under the manufacturing conditions of the second molecular sieve, and / or, in step 2), the second molecular sieve is grown in situ on the first molecular sieve containing the first template agent.

12. A composite molecular sieve, comprising a first molecular sieve and a second molecular sieve covering the surface of the first molecular sieve, wherein the first molecular sieve is a beta molecular sieve, the second molecular sieve is a MOR molecular sieve, and the mass ratio of the first molecular sieve to the second molecular sieve is (60-99):1, preferably (70-99):1, and more preferably (80-99):

1.

13. The composite molecular sieve of claim 12, wherein the average particle size of the first molecular sieve is more than 85% passing through 60 mesh (preferably more than 90% passing through 100 mesh).

14. The composite molecular sieve of claim 12, wherein the first molecular sieve and the second molecular sieve are substantially interconnected in terms of pores, and / or, the XRD pattern of the composite molecular sieve is substantially the same as the XRD pattern of the first molecular sieve, and / or, the composite molecular sieve has a bimodal pore distribution, and / or, the most probable pore sizes of the composite molecular sieve are 0.67 nm-0.72 nm (preferably about 0.69 nm) and 0.61 nm-0.66 nm (preferably about 0.64 nm), respectively, and / or, the pores with the most probable pore size of 0.67 nm-0.72 nm account for more than 80% (preferably about 90%) of the total pore volume, and / or, the BET specific surface area of ​​the composite molecular sieve is 200 m². 2 / g-650m 2 / g (preferably 250m) 2 / g-600m 2 / g), with a pore volume of 0.15ml / g-0.60ml / g (preferably 0.22ml / g-0.55ml / g).

15. The composite molecular sieve of claim 12 can be manufactured according to the manufacturing method of any one of claims 1-11.

16. A hydroisomerization catalyst (preferably a low-carbon alkane hydroisomerization catalyst) comprising the composite molecular sieve and active metal component as described in claim 12.

17. The hydroisomerization catalyst of claim 16, wherein, based on the total weight of the hydroisomerization catalyst of 100 wt%, the content (dry basis) of the composite molecular sieve is 1 wt%-80 wt% (preferably 10 wt%-70 wt%, more preferably 20 wt%-60 wt%), and the content (based on metal element) of the active metal component is 0.01 wt%-10 wt% (preferably 0.05 wt%-8.0 wt%, more preferably 0.1 wt%-5.0 wt%).

18. The hydroisomerization catalyst of claim 16, wherein the active metal component is selected from at least one noble metal element of Group VIII of the periodic table, preferably at least one of Pt and Pd, especially Pt.

19. A method for hydroisomerization, comprising the step of hydroisomerizing a low-carbon alkane in the presence of the hydroisomerization catalyst of claim 16.

20. The hydroisomerization method of claim 19, wherein the conditions for the hydroisomerization reaction include: The reaction temperature was 200℃-350℃, the reaction pressure was 1MPa-10MPa, and the volume hourly space velocity was 0.5h⁻¹. -1 -4.0h -1 .

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