A porous molecular sieve material, a preparation method and applications thereof

Abstract

The application discloses a porous molecular sieve material, which has at least three concave arcs and at least two adsorption-desorption hysteresis loops in a low-temperature nitrogen adsorption isotherm curve. A preparation method of the porous molecular sieve material comprises the following steps: mixing a molecular sieve containing silicon as a first skeleton element with polyquaternary ammonium base, water and optionally added small-molecule nitrogen-containing basic compounds, treating the mixture at a temperature of 100-200 DEG C for 1-72 hours, and separating at least part of solid products from the treatment product and drying and calcining the solid products.

Description

Technical Field

[0001] This invention relates to inorganic materials, preparation methods, and applications, and more particularly to molecular sieve materials, preparation methods, and applications. Background Technology

[0002] Porous materials, with their abundant pore structure and the advantages of adjustable pore size, active center location, and state, are highly beneficial for processes such as the transformation and adsorption of specific substrate molecules. Inorganic porous materials, in particular, are widely studied due to their inorganic elemental structure, which offers advantages such as structural stability, resistance to harsh acid and alkali conditions, and a wide range of applications. Based on their structure, inorganic porous materials can be classified into amorphous and crystalline materials. Molecular sieve materials, a type of crystalline material, are widely used in chemical catalysis, adsorption separation, and other processes.

[0003] Molecular sieves are a class of inorganic materials with unique porous structures and active centers, formed by interconnected TO4 tetrahedra. T represents a framework element in trivalent, tetravalent, or pentavalent states, and can be elements such as Si, B, Al, Ga, C, Ge, Sn, Pb, Ti, V, Zr, Hf, and P. When some T elements are substituted by elements other than Si, it can be called a heteroatom-substituted molecular sieve material. Stable fixation of heteroatoms within the molecular sieve framework can yield excellent physicochemical properties.

[0004] Molecular sieves, based on the connection pattern of TO4, can achieve regular pore structures. According to pore size, they can be classified into micropores (pores composed of 8-membered ring T atoms), mesopores (pores composed of 10-membered ring T atoms), macropores (pores composed of 12-membered ring T atoms), and super-large pores. According to the classification rules recommended by IUPAC, pore structures can be further classified by size into micropores (pore size less than 2 nm), mesopores (pore size greater than 2 nm and less than 50 nm), and macropores (pore size greater than 50 nm). In practical industrial applications, the pore size of the parent material of molecular sieves is mainly distributed within the micropore range. To obtain larger openings and better diffusion properties, further pore-enlarging treatment can be performed.

[0005] CN1301599A discloses a method for treating TS-1 molecular sieves with a solution containing an organic base to obtain a hollow titanium-silicon molecular sieve. However, the hollow structure is closed, resulting in significant resistance to substrate molecule diffusion. Furthermore, the preparation method is complex, has a long process, and high production costs.

[0006] Using inorganic alkaline solutions, such as sodium hydroxide solution, for pore-expanding treatment is more difficult than using organic alkaline solutions because inorganic alkaline solutions have poor structural guiding ability, which can easily lead to the collapse of the molecular sieve structure during the treatment process.

[0007] Silanization pore expansion is a method developed in recent years that uses silanizing reagents as synthetic pore expanders to achieve efficient pore expansion. CN108726528A, CN106145147A, CN106145148A, and CN106145149A all disclose the preparation of hierarchical titanium-silicon molecular sieves with larger mesopore volumes using an improved silanization method. However, the titanium-silicon molecular sieves prepared by this method have increased disorder in their structure and poor stability. They are more suitable for activating organic peroxides, but perform poorly in reactions using hydrogen peroxide as an oxidant.

[0008] In summary, existing technologies using pore-expansion methods to prepare molecular sieve-type inorganic porous materials suffer from problems such as simple pore structure, poor structural stability, complex preparation, high cost, and narrow applicability. Summary of the Invention

[0009] One of the objectives of this invention is to provide a porous molecular sieve material with a stable structure and pore distribution characteristics that differ from those of existing technologies.

[0010] The second objective of this invention is to provide a simple, low-cost method for preparing porous molecular sieve materials with stable structure and pore distribution characteristics different from those of existing technologies.

[0011] A third objective of this invention is to provide applications for the porous molecular sieve material of this invention, such as as a catalytic material to improve reaction conversion and product selectivity.

[0012] To achieve one of the objectives of this invention, the present invention provides a porous molecular sieve material, characterized in that its low-temperature nitrogen adsorption isotherm contains at least three concave arcs and at least two adsorption-desorption hysteresis loops.

[0013] To achieve the second objective of this invention, this invention provides a method for preparing porous molecular sieve materials, characterized in that a molecular sieve containing silicon as the first framework element is mixed with polyquaternary ammonium base, water, and optionally added small molecule nitrogen-containing basic compounds, and treated at a temperature of 100-200°C for 1-72 hours, and at least a portion of the solid product is separated from the treated product and then dried and calcined.

[0014] To achieve the third objective of this invention, this invention provides a method for applying the above-mentioned porous molecular sieve material, characterized in that the porous molecular sieve material, or the porous molecular sieve material prepared by the method, is applied to an adsorption process, a catalytic reaction, a catalyst preparation, or used as a support.

[0015] The porous molecular sieve material provided by this invention has physicochemical characterization features that differ from those of existing technologies, mainly manifested in the presence of at least three concave arcs and at least two adsorption-desorption hysteresis loops in its low-temperature nitrogen adsorption isotherm curve.

[0016] The method for preparing porous molecular sieve materials provided by this invention is simple, easy to implement, low in cost, and can prepare porous molecular sieve materials with physicochemical characterization characteristics different from those of existing technologies. It solves the problems of single pore structure, poor structural stability, and narrow applicability in the preparation of porous molecular sieve materials.

[0017] Due to its physicochemical characterization features that differ from existing technologies, the porous molecular sieve material provided by this invention exhibits excellent performance in catalytic reactions and adsorption-desorption separation processes. For example, as a catalytic material, it has better reaction conversion rate and product selectivity. Attached Figure Description

[0018] Figure 1 SEM image of the hollow titanium-silicon molecular sieve HTS sample prepared for Comparative Example 1.

[0019] Figure 2 TEM image of the hollow titanium-silicon molecular sieve HTS sample prepared for Comparative Example 1.

[0020] Figure 3 Low-temperature nitrogen adsorption-desorption curves of the hollow titanium-silicon molecular sieve HTS sample prepared for Comparative Example 1.

[0021] Figure 4 SEM image of the titanium-silicon molecular sieve comparison sample STS-D prepared for Comparative Example 2.

[0022] Figure 5 TEM image of STS-D, a comparative sample of titanium-silicon molecular sieve prepared for Comparative Example 2.

[0023] Figure 6 The low-temperature nitrogen adsorption-desorption curve of the titanium-silicon molecular sieve STS-D prepared for Comparative Example 2 is shown.

[0024] Figure 7 The XRD pattern of the porous molecular sieve material TS-1-1 prepared in Example 1.

[0025] Figure 8 The image shows a SEM image of the porous molecular sieve material TS-1-1 prepared in Example 1.

[0026] Figure 9 The image shows a TEM image of the porous molecular sieve material TS-1-1 prepared in Example 1.

[0027] Figure 10 The low-temperature nitrogen adsorption-desorption curve of the porous molecular sieve material TS-1-1 prepared in Example 1.

[0028] Figure 11 SEM image of the all-silica molecular sieve comparative sample S-1-D prepared for Comparative Example 3.

[0029] Figure 12 TEM image of the all-silica molecular sieve comparative sample S-1-D prepared for Comparative Example 3.

[0030] Figure 13 Low-temperature nitrogen adsorption-desorption curve of the all-silica molecular sieve comparative sample S-1-D prepared for Comparative Example 3.

[0031] Figure 14 SEM image of porous all-silica molecular sieve material S-1-1 prepared in Example 7.

[0032] Figure 15 Low-temperature nitrogen adsorption-desorption curves of porous all-silica molecular sieve material S-1-1 prepared in Example 7.

[0033] Figure 16 SEM image of Sn-MEL-D, a comparative sample of tin-silicon molecular sieve prepared for Comparative Example 4.

[0034] Figure 17 The low-temperature nitrogen adsorption-desorption curves of the tin-silicon molecular sieve Sn-MEL-D were prepared for Comparative Example 4.

[0035] Figure 18 SEM image of Sn-MEL porous molecular sieve material prepared in Example 10.

[0036] Figure 19 Low-temperature nitrogen adsorption-desorption curves of Sn-MEL porous molecular sieve material prepared in Example 10.

[0037] Figure 20 SEM image of the zirconium silicate molecular sieve Zr-MFI-D prepared for Comparative Example 5.

[0038] Figure 21 The low-temperature nitrogen adsorption-desorption curves of the zirconium silicon molecular sieve comparison sample Zr-MFI-D were prepared for Comparative Example 5.

[0039] Figure 22 SEM image of Zr-MFI, a porous molecular sieve material prepared in Example 11.

[0040] Figure 23 Low-temperature nitrogen adsorption-desorption curves for the porous molecular sieve material Zr-MFI prepared in Example 11. Detailed Implementation

[0041] The present invention provides a porous molecular sieve material, characterized in that its low-temperature nitrogen adsorption isotherm contains at least three concave arcs and at least two adsorption-desorption hysteresis loops.

[0042] Low-temperature nitrogen adsorption-desorption isotherms are obtained by measuring the adsorption and desorption properties of materials for nitrogen at liquid nitrogen temperatures. The shape of these isotherms can be used to determine the surface structure and pore properties of the material. The IUPAC (International Union of Pure and Applied Chemistry) classifies adsorption isotherms into six categories based on their shape. These are further subdivided into six categories based on the non-coincidence of the adsorption and desorption lines, forming a hysteresis loop. These classifications broadly distinguish the surface and pore structure characteristics of different materials.

[0043] The porous molecular sieve material of the present invention exhibits at least three concave arcs in its low-temperature nitrogen adsorption isotherm, where each concave arc is an arc formed by the curve curving inwards to one side. In contrast, conventional porous materials typically have only two or one concave arcs in their nitrogen adsorption curves. Specifically, in the porous molecular sieve material of the present invention, at least two concave arcs are located at a relative pressure (i.e., the ratio of the nitrogen adsorption pressure p to the nitrogen saturation pressure p0 at that point, p / p0) < 0.3, and one concave arc is located at a relative pressure greater than 0.7. The presence of three or more concave arcs indicates that the porous molecular sieve material of the present invention has a rich surface and pore structure.

[0044] The hysteresis loops present in the low-temperature nitrogen adsorption-desorption isotherms of porous molecular sieve materials are usually closely related to the mesopores present in the material. The hysteresis loop is defined as a ring-shaped feature formed by the non-overlapping adsorption and desorption branches. The porous molecular sieve material of this invention exhibits at least two hysteresis loops in its adsorption-desorption isotherms, indicating the presence of specific pore structure characteristics, while typical porous materials typically exhibit at most one hysteresis loop.

[0045] The porous molecular sieve material of the present invention further exhibits, in the low-temperature nitrogen adsorption-desorption isotherm curve, at least two hysteresis loops, including a first hysteresis loop and a second hysteresis loop. The first hysteresis loop is located in the range where the relative pressure p / p0 is less than 0.3, and the second hysteresis loop is located in the range where the relative pressure p / p0 is greater than 0.45. Due to the change in the surface properties of the porous molecular sieve material of the present invention, the adsorption of nitrogen in the low-pressure region is weakened, resulting in two adsorption platforms, including a first adsorption platform and a second adsorption platform. Typically, hysteresis loops in mesoporous materials begin to form in the high-pressure region from around 0.45 relative pressure, while the porous molecular sieve material of the present invention also exhibits hysteresis loops in the range where the relative pressure is less than 0.3.

[0046] The porous molecular sieve material of the present invention contains silicon as the first framework element of the molecular sieve. For example, it may contain only silicon and oxygen, existing as an all-silicon molecular sieve. Alternatively, it may contain other framework elements besides silicon and oxygen, such as one or more selected from C, Ge, Sn, Pb, Ti, Zr, Hf, B, Al, and Ga as the second framework element, existing as a heteroatom molecular sieve (TS-1, TS-2, tin-titanium-silicon molecular sieve, etc.). The framework element refers to the element that exists in the molecular sieve framework topology, is bonded to its four neighboring atoms, and exists in a tetrahedral coordination structure with other framework elements. For example, the porous molecular sieve material contains SiO2, or contains SiO2 and one or more of the framework structures of GeO2, SnO2, PdO2, TiO2, ZrO2, HfO2, C, B2O3, Al2O3, and Ga2O3. Preferably, the second framework element is selected from one or more of Ti, Sn, and Zr. For example, the porous molecular sieve material contains SiO2 and one or more of SnO2, TiO2, and ZrO2. The molar ratio of the first framework element to the second framework element is preferably 1:(0.0001-1), more preferably 1:(0.001-0.4), more preferably 1:(0.005-0.1), and most preferably 1:(0.01-0.06).

[0047] A further feature of the porous molecular sieve material of the present invention is that, upon observation using a scanning electron microscope (SEM), its surface exhibits at least one surface pore with a maximum radial dimension of not less than 5 nm. This surface pore extends into the interior of the porous molecular sieve material to form open pores. Preferably, the maximum radial dimension is not less than 10 nm, more preferably not less than 20 nm. Upon observation using a transmission electron microscope (TEM), open pores formed by the extension of the surface pores of the porous molecular sieve material particles into the interior can be observed. The pore size of these open pores is not less than 10 nm, preferably not less than 20 nm, more preferably not less than 40 nm. Because the porous molecular sieve material of the present invention has open surface pores, it can effectively reduce the diffusion path of substrate molecules, facilitating the rapid diffusion of substrate molecules to the active sites.

[0048] Optionally, in addition to the open pores described above, the porous molecular sieve material of the present invention may also contain at least one isolated (i.e., no channel connected to other pores or hollow structures in TEM images) intracrystalline hollow structure with a pore size of 5-100 nm. The porous molecular sieve material of the present invention possesses various forms of mesoporous, macroporous, and open-pore structures, which facilitates substrate molecule diffusion and enhances its application performance.

[0049] The structure of the porous molecular sieve material of the present invention can be determined by X-ray diffraction (XRD). The structure can be an amorphous structure with disordered atomic arrangement, a short-range ordered and long-range disordered amorphous structure, or a crystalline structure with regular atomic arrangement; the present invention does not impose any particular limitation. Preferably, the porous molecular sieve material of the present invention has a crystalline structure, and the atomic arrangement of its unit cells can be cubic, trigonal, tetragonal, hexagonal, orthorhombic, monoclinic, or triclinic. Preferably, the porous molecular sieve structure can be any one or more of the structure codes approved by the International Zygotes Association (IZA), for example, it can be ABW, ACO, AEI, AEL, AEN, AET, AFG, AFI, AFN, AFO, AFR, AFS, AFT, AFV, AFX, AFY, AHT, ANA, ANO, APC, APD, AST, ASV, ATN, ATO, ATS, ATT, ATV, AVE, AVL, AWO, AWW, BCT, BEC, BIK, BOF, BOG, BOZ, BPH, B RE, BSV, CAN, CAS, CDO, CFI, CGF, CGS, CHA, -CHI, -CLO, CON, CSV, CZP, DAC, DDR, DFO, DFT, DOH, DON, EAB, EDI, EEI, EMT, EON, EPI , ERI, ESV, ETL, ETR, ETV, EUO, EWO, EWS, -EWT, EZT, FAR, FAU, FER, FRA, GIS, GIU, GME, GON, GOO, HEU, IFO, IFR, -IFT, -IFU, IFW, IFY, IHW, IMF, IRN, IRR, -IRY, ISV, ITE, ITG, ITH, ITR, ITT, -ITV, ITW, IWR, IWS, IWV, IWW, JBW, JNT, JOZ, JRY, JSN, JSR, JST, JS W, KFI, LAU, LEV, LIO, -LIT, LOS, LOV, LTA, LTF, LTJ, LTL, LTN, MAR, MAZ, MEI, MEL, MEP, MER, MFI, MFS, MON, MOR, MOZ, MRT, MSE, M SO, MTF, MTN, MTT, MTW, MVY, MWF, MWW, NAB, NAT, NES, NON, NPO, NPT, NSI, OBW, OFF, OKO, OSI, OSO, OWE, -PAR, PAU, PCR, PHI, PON, POR, POS, PSI, PTO, PTT, PTY, PUN, PWN, PWO, PWW, RHO, -RON, RRO, RSN, RTE, RTH, RUT, RWR, RWY, SAF, SAO, SAS, SAT, SAV, SBE, SBN,One or more of the following topological structures are selected from SBS, SBT, SEW, SFE, SFF, SFG, SFH, SFN, SFO, SFS, SFW, SGT, SIV, SOD, SOF, SOR, SOS, SOV, SSF, -SSO, SSY, STF, STI, STT, STW, -SVR, SVV, SWY, -SYT, SZR, TER, THO, TOL, TON, TSC, TUN, UEI, UFI, UOS, UOV, UOZ, USI, UTL, UWY, VET, VFI, VNI, VSV, WEI, -WEN, YFI, YUG, and ZON. Preferably, the crystal structure of the porous molecular sieve material of the present invention is selected from one of the MFI, MEL, MWW, BEA, and SVR topological structures; more preferably, the MFI topological structure.

[0050] The porous molecular sieve material of the present invention has a distribution of micropores, mesopores, macropores, and surface open pores, and there are no particular limitations on the specific surface area and pore volume distribution of each pore structure. Optionally, the porous molecular sieve material is characterized by a BET specific surface area of ​​350-460 m² / g as determined by low-temperature nitrogen adsorption-desorption characterization. 2 / g, preferably 370-430m 2 / g, more preferably 380-420m 2 / g, micropore volume is 0.15-0.19cm³ 3 / g, preferably 0.16-0.18cm 3 / g, mesopore volume is 0.1-0.15cm³ 3 / g, preferably 0.11-0.14cm 3 / g, more preferably 0.12-0.13cm 3 / g.

[0051] The present invention also provides a method for preparing porous molecular sieve materials, characterized in that a molecular sieve containing silicon as the first framework element is mixed with polyquaternary ammonium base, water, and optionally added small molecule nitrogen-containing basic compound, and treated at a temperature of 100-200°C, preferably 130-180°C, more preferably 150-170°C for 1-72 hours, preferably 6-48 hours, more preferably 12-24 hours, and at least a portion of the solid product is separated from the treated product, and the porous molecular sieve material is obtained by drying and calcining.

[0052] In the preparation method provided by this invention, preferably, the polyquaternary ammonium base is a quaternary ammonium base polymer with an average degree of polymerization of 10-100,000, more preferably an average degree of polymerization of 100-50,000, more preferably an average degree of polymerization of 500-10,000, and most preferably an average degree of polymerization of 1,000-5,000. The average degree of polymerization refers to the average number of repeating units contained in the polymer macromolecular chain.

[0053] The polyquaternary ammonium base is preferably prepared by hydroxide exchange from at least one of the following polyquaternary ammonium salts:

[0054] Polyquaternium-2, CAS No.: 68555-36-2, poly[bis(2-chloroethyl)ether-alt-1,3-bis[3-(dimethylamino)propyl]urea]quaternized, structural formula is

[0055]

[0056] Polyquaternium-6, CAS No.: 26062-79-3, polydimethyldiallylammonium chloride, structural formula is

[0057]

[0058] Polyquaternium-7, CAS No.: 26590-05-6, a copolymer of dimethyl diallyl ammonium chloride and acrylamide, with the following structural formula:

[0059]

[0060] Polyquaternium-10, CAS No.: 68610-92-4, chlorinated 2-hydroxy-3-(trimethylamino)propyl polyoxyethylene cellulose ether, structural formula is

[0061]

[0062] Polyquaternium-11, CAS No.: 53633-54-8, a cationic polymer of vinylpyrrolidone (VP) / N,N-dimethylaminomethyl methacrylate (DMAEMA), with the following structural formula:

[0063]

[0064] Polyquaternium-22, CAS No.: 53694-17-0, dimethyl diallyl ammonium chloride-acrylic acid copolymer, structural formula is

[0065]

[0066] Polyquaternium-32, CAS No.: 35429-19-7, N,N,N-trimethyl-2-(2-methyl-1-oxo-2-propenyloxy)ethylammonium chloride-acrylamide copolymer, structural formula is

[0067]

[0068] Polyquaternium-37, CAS No.: 26161-33-1, is a homopolymer of N,N,N-trimethyl-2-[(2-methyl-1-oxo-2-propenyl)oxy]ethylamine hydrochloride, with the structural formula:

[0069]

[0070] Polyquaternium-39, CAS No.: 25136-75-8, dimethyl diallyl ammonium chloride-acrylamide-acrylic acid copolymer, structural formula is

[0071]

[0072] Polyquaternium-44, CAS No.: 150599-70-5, is a copolymer of N-vinylpyrrolidone and quaternized vinylimidazolium, with the following structural formula:

[0073]

[0074] Polyquaternium-47, CAS No.: 197969-51-0, is a polymerization of N,N,N-trimethyl-3-[(2-methyl-1-oxo-2-propenyl)amino]-1-propanenium chloride with methyl 2-acrylate and 2-acrylic acid, achieved through polymerization of the following monomers.

[0075]

[0076] Polyquaternium-51, CAS No.: 125275-25-4, methacryloyloxyethyl phosphorylcholine-n-butyl methacrylate, polymerized from the following monomers

[0077]

[0078] The inventors unexpectedly discovered that porous molecular sieve materials prepared by treatment with polyquaternary ammonium bases form new porous structures. Among the polyquaternary ammonium bases, those obtained by hydroxide exchange of polyquaternary ammonium salts-2,-6,-7,-22,-32,-37,-39, and-47 are preferred, with those obtained by hydroxide exchange of polyquaternary ammonium salts-32,-37, and-47 being the most preferred. The hydroxide exchange of the polyquaternary ammonium salts can be carried out by impregnating the polyquaternary ammonium salts with a membrane material, such as a semi-permeable membrane, in a static or flowing solution containing hydroxide ions. The hydroxide concentration in the solution containing hydroxide ions can be 0.001-5 mol OH- / L, more preferably 0.05-2 mol OH- / L, even more preferably 0.1-1 mol OH- / L, and the exchange time satisfies the degree of exchange >30%, preferably >50%, even more preferably >70%, more preferably >90%, and most preferably >98%. The degree of exchange refers to the molar percentage of anions in the polyquaternary ammonium salt that are replaced by hydroxide ions out of the total anions.

[0079] In the preparation method provided by this invention, the small molecule nitrogen-containing basic compound includes one or more of organic ammonium salts and inorganic ammonium salts with no more than 15 carbon atoms.

[0080] The organic ammonium salts include straight-chain carboxylic acid ammonium salts, cyclic carboxylic acid ammonium salts, and aromatic carboxylic acid ammonium salts with no more than 15 carbon atoms, preferably organic ammonium salts with no more than C12 carbon atoms, and more preferably organic ammonium salts with no more than C6 carbon atoms. For example, the organic ammonium salts may be, but are not limited to, one or more of ammonium formate, ammonium acetate, ammonium propionate, ammonium butyrate, ammonium valerate, ammonium cyclovalerate, ammonium hexanoate, and ammonium hexenoate.

[0081] The inorganic ammonium salt may be one or more of the following: ammonium nitrate, ammonium phosphate, diammonium hydrogen phosphate, ammonium dihydrogen phosphate, ammonium sulfate, ammonium bisulfate, ammonium sulfite, ammonium bisulfite, ammonium chloride, ammonium bromide, ammonium fluoride, ammonium carbonate, and ammonium bicarbonate. Preferably, the inorganic ammonium salt is one or more of the following: ammonium nitrate, ammonium bicarbonate, ammonium carbonate, and ammonium chloride.

[0082] In the preparation method provided by the present invention, the ratio of the molecular sieve containing silicon as the first framework element (calculated as silicon dioxide, molar) to polyquaternary ammonium base (by weight), water (by weight), and optional small molecule nitrogen-containing basic compound (molar) is 1:(0.001-0.5):(5-100):(0-0.3), preferably 1:(0.005-0.2):(10-50):(0-0.15), and more preferably 1:(0.01-0.1):(15-30):(0.02-0.08).

[0083] In the preparation method provided by the present invention, the preparation process can be carried out once or repeated multiple times, for example, it can be repeated 1-10 times, and the technical effect of the present invention can be obtained in all cases.

[0084] In the preparation method provided by the present invention, the molecular sieve containing silicon as the first framework element does not contain other four-coordinate framework elements. The molecular sieve containing silicon as the first framework element is preferably prepared by the following method: a silicon source, a quaternary ammonium base, and water are mixed to obtain a first mixture, and aged at a temperature of 5-120°C for 0.5-24 hours to obtain a sol, preferably aged at 20-100°C for 2-18 hours, more preferably aged at 40-90°C for 4-12 hours, and more preferably aged at 60-80°C for 5-10 hours; then the sol is crystallized at a temperature of 100-200°C for 2-168 hours, more preferably crystallized at 130-180°C for 12-96 hours, and more preferably crystallized at 150-170°C for 24-72 hours; finally, at least a portion of the product is separated from the mixture, and after drying and calcination, at least a portion of the molecular sieve is obtained.

[0085] In the preparation method provided by the present invention, the molecular sieve containing silicon as the first framework element may also contain a second framework element. The second framework element is selected from one or more of C, Ge, Sn, Pb, Ti, Zr, Hf, B, Al, and Ga, preferably from one or more of Sn, Ti, and Zr. The molar ratio of silicon to the second framework element is 1:(0.001-1), preferably 1:(0.005-0.3), more preferably 1:(0.01-0.1), further preferably 1:(0.015-0.06), and most preferably 1:(0.02-0.04). The molecular sieve containing silicon as the first framework element is preferably prepared by the following method: a silicon source, a second framework element source, a quaternary ammonium base, and water are mixed to obtain a first mixture, and aged at a temperature of 5-120°C for 0.5-24 hours to obtain a sol, preferably aged at 20-100°C for 2-18 hours, more preferably aged at 40-90°C for 4-12 hours, and more preferably aged at 60-80°C for 5-10 hours; then the sol is crystallized at a temperature of 100-200°C for 2-168 hours, more preferably crystallized at 130-180°C for 12-96 hours, and more preferably crystallized at 150-170°C for 24-72 hours; finally, at least a portion of the product is separated, dried, and calcined to obtain at least a portion of the molecular sieve.

[0086] The preparation method provided by this invention does not have special requirements for the silicon source in the preparation of the molecular sieve containing silicon as the first framework element. Common silicon sources known to those skilled in the art can be used as the silicon source of this invention. The silicon source is further classified into monodisperse silicon sources and aggregated silicon sources according to the degree of bonding between silicon atoms. Monodisperse silicon sources refer to silicon atoms that are not connected to other silicon atoms through silicon-oxygen-silicon bonds, while aggregated silicon sources refer to silicon atoms in at least a portion of the silicon source that are connected to other silicon atoms through silicon-oxygen-silicon bonds.

[0087] The silicon source can be a monodisperse silicon source and / or an aggregated silicon source. Preferably, both monodisperse and aggregated silicon sources are used simultaneously. The monodisperse silicon source includes tetraalkoxysilane, specifically, one or more of methyl orthosilicate, ethyl orthosilicate, propyl orthosilicate, and butyl orthosilicate. The aggregated silicon source includes silica, silica gel, and silica sol. The molar ratio of the monodisperse silicon source to the aggregated silicon source (based on silica) is preferably 1:(0.1-10), more preferably 1:(0.5-7), further preferably 1:(1-5), and even more preferably 1:(2-4). Silicon sources with a silica content (by weight) greater than 80%, 90%, 95%, or 99% (based on dry silica) can be used, preferably greater than 95%, and more preferably greater than 99%. The dry basis silica content refers to the (weight) content of silica in the chemical composition of the silicon source obtained by XRF testing after the silicon source has been dried and dehydrated and calcined at 880℃ for 3 hours.

[0088] In the method for preparing the molecular sieve containing silicon as the first framework element, when the second framework element is C, the second framework element source has a structure of A1A2A3Si-A4-SiA5A6A7, wherein A1, A2, A3, A5, A6, and A7 are each independently C1-C10 alkoxy or halogen groups with or without substitution, and A4 is a C1-C3 alkyl group; preferably, A1, A2, A3, A5, A6, and A7 are each independently C1-C8 alkoxy or halogen groups, and A4 is a C1-C2 alkyl group; more preferably, A1, A2, A3, A5, A6, and A7 are each independently C1-C3 alkoxy or halogen groups, and A4 is a C1 alkyl group. For example, when the second skeleton element is C, the source of the second skeleton element can be one or more of bis(trimethoxysilyl)methane, bis(triethoxysilyl)methane, bis(tripropoxysilyl)methane, bis(trichlorosilyl)methane, and bis(diethoxychlorosilyl)methane.

[0089] In the method for preparing a molecular sieve containing silicon as the first framework element, when the second framework element is Ge, the source of the second framework element can be a common germanium source well known to those skilled in the art. For example, the source of the second framework element when the second framework element is Ge can be an oxide, salt, or organometallic salt of germanium. More specifically, it can be one or more of germanium monoxide, germanium dioxide, germanium tetrafluoride, germanium tetrachloride, germanium tetrabromide, germanium tetraiodide, germanium sulfide, tetramethylgermanium, tetraethylgermanium, tetrapropylgermanium, tetrabutylgermanium, methylgermanane, ethylgermanane, propylgermanane, and butylgermanane.

[0090] In the method for preparing a molecular sieve containing silicon as the first framework element, when the second framework element is Sn, the source of the second framework element can be a common tin source well known to those skilled in the art. For example, when the second framework element is Sn, the source of the second framework element can be an oxide, salt, or organometallic salt of tin. More specifically, it can be one or more of tin dioxide, stannous oxide, stannous chloride, stannous trichloride, stannous tetrachloride, potassium stannate, sodium stannate, metastannic acid, stannic acid, tetramethyltin, tetraethyltin, tetrapropyltin, and tetrabutyltin.

[0091] In the method for preparing a molecular sieve containing silicon as the first framework element, when the second framework element is Pb, the source of the second framework element can be a common lead source well known to those skilled in the art. For example, when the second framework element is Pb, the source of the second framework element can be lead oxides, salts, organometallic salts, or more specifically, one or more of lead oxide, lead chloride, lead nitrate, lead sulfate, and lead acetate.

[0092] In the method for preparing a molecular sieve containing silicon as the first framework element, when the second framework element is Ti, the source of the second framework element can be a common titanium source well known to those skilled in the art. For example, titanium salts or organometallic salts. More specifically, it can be at least one of tetraalkoxytitanium, titanium tetrachloride, titanium trichloride, titanium sulfate, fluorotitanic acid, titanium dichlorocerocene, and titanium nitrate; more preferably, it includes tetraalkoxytitanium or titanium tetrachloride; and most preferably, it includes at least one of tetraethyl titanate, tetrapropyl titanate, and tetrabutyl titanate.

[0093] In the method for preparing molecular sieves containing silicon as the first framework element, when the second framework element is Zr, the source of the second framework element can be a common zirconium source well known to those skilled in the art. For example, zirconium salts or organometallic salts. More specifically, it can be one or more of zirconium tetrachloride, zirconium trichloride, zirconium oxychloride, zirconium oxysulfate, zirconium nitrate, zirconium acetate, and zirconium tetraalkoxy.

[0094] In the method for preparing a molecular sieve containing silicon as the first framework element, when the second framework element is Hf, the source of the second framework element can be a common hafnium source well known to those skilled in the art. For example, hafnium oxides, salts, organometallic salts, and more specifically, one or more of hafnium oxide, hafnium tetrachloride, hafnium hydroxide, hafnium carbide, and hafnium boride.

[0095] In the method for preparing a molecular sieve containing silicon as the first framework element, when the second framework element is B, the source of the second framework element can be a common boron source well known to those skilled in the art. For example, boron oxides, salts, organoboron salts, and more specifically, one or more of boron oxide, boric acid, borax, alkylboron compounds, and alkoxyboron compounds.

[0096] In the method for preparing a molecular sieve containing silicon as the first framework element, when the second framework element is Al, the source of the second framework element can be a common aluminum source well known to those skilled in the art. For example, aluminum oxides, salts, organoaluminum compounds; more specifically, it can be one or more of alumina, aluminum trichloride, aluminum sulfate, aluminum nitrate, aluminum phosphate, sodium aluminate, aluminum acetate, alkyl aluminum compounds, and alkoxy aluminum compounds.

[0097] In the method for preparing a molecular sieve containing silicon as the first framework element, when the second framework element is Ga, the source of the second framework element can be a common gallium source well known to those skilled in the art. For example, gallium oxides, salts, organogallium compounds; more specifically, it can be one or more of gallium oxide, gallium chloride, gallium sulfate, gallium nitrate, gallium phosphate, sodium gallate, gallium acetate, alkyl gallium compounds, and alkoxy gallium compounds.

[0098] In the method for preparing the molecular sieve containing silicon as the first framework element, the quaternary ammonium base has the following structure: R1R2R3R4N. + OH -In the structure, R1, R2, R3, and R4 are independent C2-C5 normal or isomeric alkyl or alkenyl groups, or halogenated (fluorine, chlorine, bromine, iodine), nitro, amino, hydroxyl, carboxyl, carbonyl, aldehyde, ketone, ether, ester, sulfonic acid, cyano, amide, or acyl halide-substituted C2-C5 normal or isomeric alkyl or alkenyl groups. For example, they can be ethyl, n-propyl, isopropyl, etc. 1-Butyl, n-Butyl, Isobutyl, tert-Butyl, n-Pentyl, 3-Methylbutyl, 2,2-Dimethylpropyl, 1-Methylbutyl, 1-Ethylpropyl, 1,2-Dimethylpropyl, 1,1-Dimethylpropyl, Vinyl, Propylene, Allyl, Isopropenyl, 1-Butenyl, 2-Butenyl, 3-Butenyl, 2-Methyl-1-Propylene, 2-Methyl-2-Propylene, 1,1-Dimethylvinyl, 1-Pentene 2-Pentenyl, 3-Pentenyl, 4-Pentenyl, 3-Methyl-1-butenyl, 3-Methyl-2-butenyl, 3-Methyl-3-butenyl, 2,2-Dimethyl-1-propenyl, 2,2-Dimethyl-2-propenyl, 1-Methyl-1-butenyl, 1-Methyl-2-butenyl, 1-Methyl-3-butenyl, 1-Ethyl-1-propenyl, 1-Ethyl-2-propenyl, 1,2-Dimethyl One of the following: -1-propenyl, 1,2-dimethyl-2-propenyl, 1,1-dimethyl-1-propenyl, 1,1-dimethyl-2-propenyl, chloroethyl, chloropropyl, 2,3-dichloropropyl, chlorobutyl, chloropentyl, 1-hydroxyethyl, 1-hydroxypropyl, 2-hydroxypropyl, 3-hydroxypropyl, 2-chloro-3-hydroxypropyl, 2-hydroxy-3-chloropropyl, 2-aminopropyl, and 3-aminopropyl. Preferably, R1, R2, R3, and R4 are each independent C3 normal or isomeric alkyl or alkenyl groups, or C3 normal or isomeric alkyl or alkenyl groups substituted with halogen (fluorine, chlorine, bromine, iodine), nitro, amino, hydroxy, carboxyl, carbonyl, aldehyde, ketone, ether, ester, sulfonic acid, cyano, amide, or acyl halide. For example, they can be one of n-propyl, isopropyl, chloropropyl, 2,3-dichloropropyl, 1-hydroxypropyl, 2-hydroxypropyl, 3-hydroxypropyl, 2-chloro-3-hydroxypropyl, 2-hydroxy-3-chloropropyl, 2-aminopropyl, and 3-aminopropyl.

[0099] In the method for preparing the molecular sieve containing silicon as the first framework element, the quaternary ammonium base can exist in the form of hydroxide ions, or in the form of hydroxide ions coexisting with other anions (e.g., fluorine, chloride, bromine, iodine, nitrate, sulfate, phosphate, etc.). The molar percentage of the quaternary ammonium base existing in the form of hydroxide ions in the total quaternary ammonium base can be >5%, preferably >20%, more preferably >50%, more preferably >80%, more preferably >90%, and most preferably >99%.

[0100] In the method for preparing the molecular sieve containing silicon as the first framework element, preferably, the molar composition of silicon source, quaternary ammonium base and water is 1:(0.05-0.3):(5-60), more preferably 1:(0.08-0.25):(10-50), and even more preferably 1:(0.12-0.2):(15-30).

[0101] In the method for preparing the molecular sieve containing silicon as the first framework element, optionally, a material with a crystalline structure can be added before crystallization treatment. The weight ratio of the crystalline material to the silicon source (based on SiO2) is (0.001-2):1, preferably (0.005-1):1, more preferably (0.01-0.7):1, and even more preferably (0.03-0.3):1. Preferably, the crystalline material has an MFI structure and contains one or more of the elements Si, O, or Si, O, C, Si, Ge, Sn, Pb, Ti, Zr, Hf, V, B, Al, and Ga. For example, it can be at least one of the following: all-silicon molecular sieve, silicon-aluminum molecular sieve, silicon-boron molecular sieve, titanium-silicon molecular sieve, tin-silicon molecular sieve, zirconium-silicon molecular sieve, vanadium-silicon molecular sieve, silicon-gallium molecular sieve, silicon-lead molecular sieve, and silicon-hafnium molecular sieve. Preferably, the crystal material is at least one of the following: all-silicon molecular sieve, titanium-silicon molecular sieve, zirconium-silicon molecular sieve, tin-silicon molecular sieve, and borosilicate molecular sieve.

[0102] In the preparation method provided by this invention, the operation of separating at least a portion of the solid product from the processed product includes methods capable of solid-liquid separation such as filtration, sedimentation, evaporation, membrane separation, and adsorption separation. This invention has no particular limitations. The drying can be carried out at room temperature to 200°C, preferably 50-160°C, more preferably 80-140°C, under an inert gas atmosphere or an oxygen-containing gas atmosphere. The processing time is sufficient to ensure that the solid water content (by weight) is less than 30%, preferably less than 10%, more preferably less than 5%, for example, 0.5-24 hours. The calcination can be carried out at 300-800°C, preferably 400-700°C, more preferably 500-600°C, under an inert gas atmosphere or an oxygen-containing gas atmosphere. The processing time is sufficient to ensure that the solid organic matter content (by weight) is less than 5%, preferably less than 1%, more preferably less than 0.1%, for example, 0.5-24 hours.

[0103] The present invention also provides porous molecular sieve materials obtained by the above preparation method.

[0104] The present invention further provides a method for applying the above-mentioned porous molecular sieve material.

[0105] The porous molecular sieve material of the present invention can be applied to adsorption processes, catalyst preparation, catalytic reactions, or used as a support.

[0106] The adsorption process described herein can be a process in which the porous molecular sieve material of the present invention is used as an adsorbent for the adsorption and separation of hydrocarbons, gases, inorganic substances, etc.

[0107] The catalyst can be prepared by using the porous molecular sieve catalytic material of the present invention as the catalytic active component, utilizing its unique framework elements, or by using it as a support to further load active centers, or by using it with other catalysts, co-catalysts, structural aids, electronic aids, binders, inert supports, etc., through mechanical mixing, kneading molding, tablet molding, extrusion molding, spray molding, ball rolling molding, oil column molding, etc.

[0108] The catalytic reaction described herein can be achieved by directly using the porous molecular sieve catalytic material of the present invention as a catalyst or by further preparing a catalyst for use in the catalytic reaction. The catalytic reaction includes, but is not limited to, oxidation reactions (oxidation / epoxidation of olefins to prepare aldehydes, ketones, acids, epoxides, and vicinal diols; oxidation of alkanes to prepare alcohols, aldehydes, and acids; oxidation of alcohols to prepare ketones and acids; oxidation of aldehydes to prepare acids; oxidation of aromatics to prepare phenols; oxidation of thioethers to prepare sulfoxides and sulfones), reduction reactions, oxime reactions (ammoniation of aldehydes / ketones to prepare amides and lactams), aldol condensation reactions, substitution / halogenation reactions, elimination reactions, transesterification reactions, dehydration reactions, etherification reactions, esterification reactions, double / triple bond addition reactions, diene addition reactions, Beckmann rearrangement reactions (gas-phase rearrangement of cyclohexanone oxime to prepare caprolactam), hydrogen transfer reactions, etc.

[0109] The aforementioned "carrier" can refer to using the porous molecular sieve catalytic material of the present invention as a carrier to load other active components.

[0110] In the application method of the porous molecular sieve material provided by the present invention, the porous molecular sieve catalytic material can be used in powder form or in the form of shaped spheres, strips, cakes, granules, etc., and can be mixed with other catalysts; the application can be carried out in various reactors such as batch reactors, slurry bed reactors, fixed bed reactors, fluidized bed reactors, moving bed reactors, and microchannel reactors; the reaction raw materials and catalysts can be fed at once, intermittently, or continuously, and the present invention does not limit them.

[0111] Those skilled in the art will understand that in the application of the porous molecular sieve material of the present invention, the separation of products and catalysts can be achieved in various ways. For example, when using raw powdered molecular sieves as catalysts, the separation of products and the recycling and reuse of catalysts can be achieved through sedimentation, filtration, centrifugation, evaporation, membrane separation, etc. Alternatively, the catalyst can be shaped and loaded into a fixed-bed reactor, and the catalyst can be recovered after the reaction is completed. Various methods for the separation and recovery of catalysts are involved in the existing literature and will not be described in detail here.

[0112] The present invention will be further illustrated by the following examples, but these examples are not intended to limit the scope of the invention.

[0113] In the following embodiments and comparative examples:

[0114] The phase structure and relative crystallinity of the molecular sieve were determined by XRD analysis. The instrument used for characterization was a Philips Panalytical Empyrean X-ray diffractometer. The test conditions were: Cu target, Kα radiation, Ni filter, tube voltage 40 kV, tube current 40 mA, scintillation counter, step size 0.0131°, scan range 5°–35°. The relative crystallinity of the molecular sieve was calculated based on the peak area of ​​the "five-finger peak" within the range of 2θ = 22°–26°. The chemical composition of the molecular sieve and the elemental ratio of heteroatoms to silicon were determined by XRF analysis. The instrument used for characterization was a Rigaku Electric Co., Ltd. 3013 X-ray fluorescence spectrometer. The test conditions were: tungsten target, excitation voltage 40 kV, excitation current 250 mA. After sample pelleting, fluorescence was emitted under X-ray irradiation. The relationship between the fluorescence wavelength (λ) and the atomic number (Z) of the element was: λ = K(ZS)⁻², where K is a constant. The element can be identified by measuring the wavelength of fluorescence. Semi-quantitative analysis is performed by measuring the intensity of characteristic spectral lines of each element using a scintillation counter and a proportional counter.

[0115] The specific surface area of ​​micropores was measured by nitrogen low-temperature adsorption-desorption method and calculated by BET method; pore volume and pore distribution were determined according to the method described in RIPP151-90 of "Analytical Methods for Petrochemical Industry" (published by Science Press in September 1990, first edition) compiled by Yang Cuiding et al.

[0116] The morphology of the molecular sieves was determined by SEM. The instrument used for analysis was a Hitachi S4800 high-resolution cold field emission scanning electron microscope with an accelerating voltage of 20 kV.

[0117] The hollow morphology of the molecular sieve was determined using TEM. The instrument used was a Tecnai G2F20S-TWIN transmission electron microscope (TEM) manufactured by FEI. The analytical method involved dispersing the sample in an ethanol solution, placing it on a sample grid, drying it, and then performing the measurements. The accelerating voltage was 200 kV.

[0118] Unless otherwise specified, all raw materials used in the examples and comparative examples are analytical grade reagents.

[0119] The catalytic reaction products were analyzed by gas chromatography, and the results were quantified using the external standard method. The chromatographic conditions were as follows: Agilent-6890 chromatograph, HP-5 capillary column, injection volume 0.5 μL, injection port temperature 280℃. Column temperature was held at 100℃ for 2 min, then increased to 250℃ at a rate of 15℃ / min and held for 10 min. An FID detector was used, with a detector temperature of 300℃.

[0120] In the examples and comparative examples:

[0121] Titanium silicate molecular sieves were evaluated using the cyclohexanone ammoniation reaction, under the following reaction conditions:

[0122] Cyclohexanone undergoes an ammoniation reaction with hydrogen peroxide and ammonia in the presence of a catalyst to yield cyclohexanone oxime. Cyclohexanone, hydrogen peroxide (30 wt%), ammonia (wt%), and tert-butanol were added to a three-necked flask in a molar ratio of 1:1.1:2:10, followed by the addition of a catalyst at 5% by weight of cyclohexanone. The reaction was refluxed at 80°C and 400 rpm for 1 h with stirring. The product was then cooled, and the liquid was separated for chromatographic analysis.

[0123] The evaluation criteria are as follows:

[0124] Cyclohexanone conversion rate (%) = (moles of cyclohexanone in feedstock - moles of cyclohexanone in product) / moles of cyclohexanone in feedstock × 100%

[0125] Cyclohexanone oxime selectivity (%) = (Number of moles of cyclohexanone oxime formed in the product) / (Number of moles of cyclohexanone in the feedstock - Number of moles of cyclohexanone in the product) × 100%

[0126] All-silica molecular sieves were evaluated using the gas-phase rearrangement of cyclohexanone oxime to produce caprolactam. The reaction conditions were as follows:

[0127] Cyclohexanone oxime undergoes a gas-phase rearrangement reaction to produce caprolactam under the catalysis of an all-silica molecular sieve. Molecular sieve tablets (40-60 mesh) are sieved and 5g is packed into a fixed-bed reactor. Cyclohexanone oxime is mixed with methanol solvent at a molar ratio of 1:20. The cyclohexanone oxime solution is pumped into the fixed-bed reactor at a space velocity of 10 h⁻¹, and the reaction is carried out at 380 °C. The product is then condensed and analyzed chromatographically.

[0128] The evaluation criteria are as follows:

[0129] Cyclohexanone oxime conversion rate (%) = (Amount of cyclohexanone oxime in feed per unit time - Amount of cyclohexanone oxime in product per unit time) / Amount of cyclohexanone oxime in feed per unit time × 100%

[0130] Caprolactam selectivity (%) = (Number of moles of caprolactam generated in the product / Number of moles of cyclohexanone oxime consumed in all products) × 100%

[0131] Tin-silicon molecular sieves were evaluated using the BV oxidation reaction of cyclohexanone, under the following reaction conditions:

[0132] Cyclohexanone and hydrogen peroxide react in a tin-silicon molecular sieve to produce ε-caprolactone. Cyclohexanone and hydrogen peroxide were added to a three-necked flask at a molar ratio of 1:2, with the catalyst added at 5% of the weight of cyclohexanone. 1,4-Dioxane was used as the solvent, with a solvent-to-cyclohexanone molar ratio of 20:1. The mixture was refluxed at 80°C for 8 hours with stirring at 400 rpm. After cooling, the liquid product was separated and analyzed by gas chromatography.

[0133] The evaluation criteria are as follows:

[0134] Cyclohexanone conversion rate (%) = (moles of cyclohexanone in feedstock - moles of cyclohexanone in product) / moles of cyclohexanone in feedstock × 100%

[0135] ε-caprolactone selectivity (%) = (moles of ε-caprolactone formed in the product) / (moles of cyclohexanone in the feed - moles of cyclohexanone in the product) × 100%

[0136] The zirconium silicate molecular sieve was evaluated using the MPV reaction to reduce levulinic acid and isopropanol, followed by further esterification to prepare γ-valerolactone. The reaction process is illustrated below:

[0137]

[0138] Step (1) is catalyzed by zirconium silicate molecular sieve, and step (2) can occur under non-catalytic conditions (such as heating). The weight ratio of zirconium silicate molecular sieve to levulinic acid is 0.05:1, the molar ratio of levulinic acid to isopropanol is 1:20, the reaction temperature is 80℃, the reaction time is 8h, and the liquid phase product is separated and analyzed by chromatography after the reaction is complete.

[0139] The evaluation criteria are as follows:

[0140] Conversion rate of levulinic acid (%) = (Moles of levulinic acid in the feed - Moles of levulinic acid in the product) / Moles of levulinic acid in the feed × 100%

[0141] γ-Valactone yield (%) = (moles of γ-valactone in the product / moles of levulinic acid in the feed) × 100%

[0142] Preparation Example 1

[0143] This preparation example illustrates the preparation of polyquaternary ammonium base compounds.

[0144] 10g of commercially available polyquaternium-2 with a degree of polymerization of 4500 was placed in a semi-permeable membrane and then immersed in a 0.5mol / L sodium hydroxide solution for hydroxide ion exchange under stirring. Each exchange lasted 24 hours. After each exchange, the sodium hydroxide solution was replaced, and the next exchange was performed, for a total of 4 exchanges. The degree of exchange was calculated to be 99% based on ion concentration. The product was then drained and named polyquaternium-2 for later use.

[0145] Polyquaternium-6, polyquaternium-7, polyquaternium-22, polyquaternium-32, polyquaternium-37, and polyquaternium-47 were treated in the same way to obtain polyquaternium-6, polyquaternium-7, polyquaternium-22, polyquaternium-32, polyquaternium-37, and polyquaternium-47, respectively, for later use.

[0146] Preparation Example 2

[0147] This preparation example illustrates the preparation of titanium-silicon MFI type molecular sieve TS-1.

[0148] A solution of silicon source (tetraethyl orthosilicate and silica, calculated as silicon dioxide), tetrabutyl titanate, tetrapropylammonium hydroxide (25 wt%, hydroxide purity greater than 99.5%), and water were mixed in a molar ratio of 1 (tetraethyl orthosilicate: silica = 1:2):0.04:0.15:25 and aged at 80°C for 6 h to obtain a sol. The sol was then crystallized at 170°C for 48 h. Finally, the solid product was obtained by filtration from the slurry, and further dried at 120°C for 6 h and calcined at 550°C for 6 h to obtain TS-1 molecular sieve.

[0149] Preparation Example 3

[0150] This preparation example illustrates the preparation of all-silica MFI molecular sieve S-1.

[0151] A silicon source (tetraethyl orthosilicate and silica, calculated as silicon dioxide), a tetrapropylammonium hydroxide solution (25 wt%, hydroxide purity greater than 99.5%), and water were mixed in a molar ratio of 1 (tetraethyl orthosilicate: silica = 1:4):0.2:30 and aged at 60°C for 10 h to obtain a sol. The sol was then crystallized at 170°C for 72 h. Finally, the solid product was obtained by filtration from the slurry, and further dried at 120°C for 6 h and calcined at 550°C for 6 h to obtain S-1 molecular sieve.

[0152] Preparation Example 4

[0153] This preparation example illustrates the preparation of Sn-MEL, a tin-silicon MEL-type molecular sieve.

[0154] A solution of silicon source (tetraethyl orthosilicate and silica, calculated as silicon dioxide), stannous chloride, tetrabutylammonium hydroxide (25 wt%, hydroxide purity greater than 99.5%), and water were mixed in a molar ratio of 1 (tetraethyl orthosilicate: silica = 1:2):0.02:0.2:30 and aged at 70°C for 5 h to obtain a sol. The sol was then crystallized at 170°C for 24 h. Finally, the solid product was obtained by filtration from the slurry, and further dried at 120°C for 6 h and calcined at 550°C for 6 h to obtain Sn-MEL molecular sieve.

[0155] Preparation Example 5

[0156] This preparation example illustrates the preparation of zirconium-silicon MFI type molecular sieve Zr-MFI.

[0157] A solution of silicon source (tetraethyl orthosilicate and silica, calculated as silicon dioxide), zirconium n-propoxide, tetrapropylammonium hydroxide (25 wt%, hydroxide purity greater than 99.5%), and water were mixed in a molar ratio of 1 (tetraethyl orthosilicate: silica = 1:2):0.02:0.2:30 and aged at 80°C for 5 h to obtain a sol. The sol was then crystallized at 170°C for 72 h. Finally, the solid product was obtained by filtration from the slurry, and further dried at 120°C for 6 h and calcined at 550°C for 6 h to obtain Zr-MFI molecular sieve.

[0158] Comparative Example 1

[0159] This comparative example illustrates the preparation, characterization, and evaluation of hollow titanium-silicon molecular sieves (HTS).

[0160] Hollow titanium-silicon molecular sieve HTS was prepared according to the method described in Example 1 of Chinese Patent CN1301599A. Hollow titanium-silicon molecular sieve HTS was obtained by rearranging the TS-1 molecular sieve of Preparation Example 2.

[0161] The hollow titanium-silicon molecular sieve HTS was characterized.

[0162] XRD analysis showed that the HTS molecular sieve has an MFI structure.

[0163] SEM results show that ( Figure 1 Hollow titanium silicon molecular sieve (HTS) exhibits a small-crystal aggregate growth morphology, and the surface of the molecular sieve has no open pores.

[0164] TEM results show that ( Figure 2 Hollow titanium-silicon molecular sieve (HTS) has multiple intracrystalline hollow structures and no open mesopores.

[0165] The nitrogen adsorption-desorption characterization results show that ( Figure 3The nitrogen adsorption curve of hollow titanium-silicon molecular sieve (HTS) has two concave arcs, one located at p / p0 less than 0.3 and the other located at p / p0 greater than 0.7; there is a hysteresis loop after p / p0 > 0.45.

[0166] The chemical composition, specific surface area, and pore volume characterization results are shown in Table 1.

[0167] The cyclohexanone ammoniation reaction of hollow titanium silica molecular sieve HTS was evaluated, and the results are shown in Table 1.

[0168] Comparative Example 2

[0169] This comparative example illustrates the preparation, characterization, and evaluation of STS-D titanium-silicon molecular sieves produced by the silanization method.

[0170] Tetrabutyl tetrasilicate, tetrapropylammonium hydroxide, and water were mixed and treated at 30°C for 12 h to obtain a silicon-titanium colloid with a molar composition of SiO2:TiO2:tetrapropylammonium hydroxide:water = 1:0.04:0.15:25. The silicon-titanium colloid was then treated at 90°C for 12 h. The treated product (based on SiO2) was then mixed with a silanizing agent, N-phenyl-3-aminopropyltrimethoxysilane, at a molar ratio of 1:0.1, and crystallized at 170°C for 48 h. The crystallized product was filtered, washed, dried at 120°C for 6 h, and calcined at 550°C for 6 h to obtain the comparative sample STS-D, a titanium-silicon molecular sieve with expanded pores using a silanizing agent.

[0171] The STS-D titanium silicate molecular sieve with pore-expanding silanizing reagent was characterized:

[0172] XRD analysis showed that the STS-D molecular sieve has an MFI structure.

[0173] SEM results show that ( Figure 4 STS-D molecular sieves exhibit a small-crystal accumulation growth morphology, and the surface of the molecular sieve has no open pores.

[0174] TEM results show that ( Figure 5 STS-D has a loosely packed morphology of "sponge-like" small particles, without open mesopores or hollow structures.

[0175] The nitrogen adsorption-desorption characterization results show that ( Figure 6 The nitrogen adsorption curve of STS-D has two concave arcs, one located at p / p0 less than 0.3 and the other located at p / p0 greater than 0.7; there is a hysteresis loop after p / p0 > 0.45.

[0176] The chemical composition, specific surface area, and pore volume characterization results are shown in Table 1.

[0177] The cyclohexanone ammonium oxime reaction of the titanium silicate molecular sieve with pore-expanding silanizing reagent was evaluated, and the results are shown in Table 1.

[0178] Example 1

[0179] This embodiment illustrates the preparation, characterization, and evaluation of the porous molecular sieve material TS-1-1 of the present invention.

[0180] The titanium-silicon molecular sieve obtained in Preparation Example 2 was mixed with polyquaternary ammonium base-47, water, and ammonium bicarbonate in a ratio of molecular sieve (moles): polyquaternary ammonium base (weight): water (weight): nitrogen-containing basic compound (moles) of 1:0.1:20:0.05. The mixture was treated at 150°C for 18 hours, and then filtered to obtain a solid product. The solid product was further dried at 120°C for 6 hours and calcined at 550°C for 6 hours to obtain TS-1-1 porous molecular sieve material.

[0181] Characterization of porous molecular sieve material TS-1-1:

[0182] XRD analysis showed that TS-1-1 molecular sieve has an MFI structure. Figure 7 ).

[0183] SEM results show that ( Figure 8 TS-1-1 molecular sieve has open pores with a size of not less than 20 nm on its surface.

[0184] TEM results show that ( Figure 9 The open pore diameter of TS-1-1 molecular sieve is not less than 20 nm; at the same time, it can be observed that some molecular sieve crystals have isolated hollow structures.

[0185] The nitrogen adsorption-desorption characterization results show that ( Figure 10 The nitrogen adsorption curve of TS-1-1 molecular sieve has four concave arcs, three of which are located at p / p0 less than 0.3 and one is located at p / p0 greater than 0.7; there are two hysteresis loops, the first of which is located in the range of relative pressure p / p0 less than 0.3 and the second of which is located in the range of relative pressure p / p0 greater than 0.45.

[0186] The chemical composition, specific surface area, and pore volume characterization results are shown in Table 1.

[0187] The cyclohexanone ammoniation reaction of porous molecular sieve material TS-1-1 was evaluated, and the results are shown in Table 1.

[0188] Example 2

[0189] This embodiment illustrates the preparation, characterization, and evaluation of the porous molecular sieve material TS-1-2 of the present invention.

[0190] The titanium-silicon molecular sieve obtained in Preparation Example 2 was mixed with polyquaternary ammonium base-32, water, and ammonium nitrate in a ratio of molecular sieve (moles): polyquaternary ammonium base (weight): water (weight): nitrogen-containing basic compound (moles) of 1:0.05:15:0.02. The mixture was treated at 160°C for 24 hours, and then the solid product was obtained by filtration. The solid product was further dried at 120°C for 6 hours and calcined at 550°C for 6 hours to obtain TS-1-2 porous molecular sieve material.

[0191] Characterization of porous molecular sieve material TS-1-2:

[0192] XRD analysis showed that TS-1-2 molecular sieve has an MFI structure.

[0193] SEM results showed that the surface of the TS-1-2 molecular sieve contained open pores with a size of not less than 30 nm.

[0194] TEM results show that the diameter of the open pores in the TS-1-2 molecular sieve is not less than 40 nm; at the same time, isolated hollow structures can be observed in some molecular sieve grains.

[0195] The nitrogen adsorption-desorption characterization results showed that the nitrogen adsorption curve of TS-1-2 molecular sieve had three concave arcs, two of which were located at p / p0 less than 0.3 and one was located at p / p0 greater than 0.7; there were two hysteresis loops, the first of which was located in the range of relative pressure p / p0 less than 0.3 and the second of which was located in the range of relative pressure p / p0 greater than 0.45.

[0196] The chemical composition, specific surface area, and pore volume characterization results are shown in Table 1.

[0197] The cyclohexanone ammoniation reaction of porous molecular sieve material TS-1-2 was evaluated, and the results are shown in Table 1.

[0198] Example 3

[0199] This embodiment illustrates the preparation, characterization, and evaluation of the porous molecular sieve material TS-1-3 of the present invention.

[0200] The titanium-silicon molecular sieve obtained in Preparation Example 2 was mixed with polyquaternary ammonium base-37, water, and ammonium carbonate in a ratio of molecular sieve (molar): polyquaternary ammonium base (weight): water (weight): nitrogen-containing basic compound (molar) of 1:0.01:30:0.08. The mixture was treated at 170°C for 12 hours, and then filtered to obtain a solid product. This solid product was further dried at 120°C for 6 hours and calcined at 550°C for 6 hours. This preparation process was repeated twice to obtain the TS-1-3 porous molecular sieve material.

[0201] Characterization of porous molecular sieve material TS-1-3:

[0202] XRD analysis showed that TS-1-3 molecular sieve has an MFI structure.

[0203] SEM results showed that the surface of TS-1-3 molecular sieve contained open pores with a size of not less than 40 nm.

[0204] TEM results show that the open pore size of the TS-1-3 molecular sieve is not less than 40 nm; at the same time, isolated hollow structures can be observed in some molecular sieve grains.

[0205] The nitrogen adsorption-desorption characterization results showed that the nitrogen adsorption curve of TS-1-3 molecular sieve had three concave arcs, two of which were located at p / p0 less than 0.3 and one was located at p / p0 greater than 0.7; there were two hysteresis loops, the first of which was located in the range of relative pressure p / p0 less than 0.3 and the second of which was located in the range of relative pressure p / p0 greater than 0.45.

[0206] The chemical composition, specific surface area, and pore volume characterization results are shown in Table 1.

[0207] The cyclohexanone ammoniation reaction of porous molecular sieve material TS-1-3 was evaluated, and the results are shown in Table 1.

[0208] Example 4

[0209] This embodiment illustrates the preparation, characterization, and evaluation of the porous molecular sieve material TS-1-4 of the present invention.

[0210] The titanium-silicon molecular sieve obtained in Preparation Example 2 was mixed with polyquaternium-6 and water in a ratio of molecular sieve (molar): polyquaternium-6 (weight): water (weight) of 1:0.008:20. The mixture was treated at 170°C for 6 hours, and then filtered from the product to obtain a solid product. The solid product was further dried at 120°C for 6 hours and calcined at 550°C for 6 hours to obtain TS-1-4 porous molecular sieve material.

[0211] Characterization of porous molecular sieve material TS-1-4:

[0212] XRD analysis showed that TS-1-4 molecular sieve has an MFI structure.

[0213] SEM results showed that the surface of TS-1-4 molecular sieve contained open pores with a size of not less than 15 nm.

[0214] TEM results show that the open pore size of the TS-1-4 molecular sieve is not less than 20 nm; no isolated hollow structures were observed in the molecular sieve grains.

[0215] The nitrogen adsorption-desorption characterization results showed that the nitrogen adsorption curve of TS-1-4 molecular sieve had three concave arcs, two of which were located at p / p0 less than 0.3 and one was located at p / p0 greater than 0.7; there were two hysteresis loops, the first of which was located in the range of relative pressure p / p0 less than 0.3 and the second of which was located in the range of relative pressure p / p0 greater than 0.45.

[0216] The chemical composition, specific surface area, and pore volume characterization results are shown in Table 1.

[0217] The cyclohexanone ammoniation reaction of porous molecular sieve material TS-1-4 was evaluated, and the results are shown in Table 1.

[0218] Example 5

[0219] This embodiment illustrates the preparation, characterization, and evaluation of the porous molecular sieve material TS-1-5 of the present invention.

[0220] The titanium-silicon molecular sieve obtained in Preparation Example 2 was mixed with polyquaternium-22 and water in a ratio of molecular sieve (molar): polyquaternium-22 (weight): water (weight) of 1:0.12:30. The mixture was treated at 150°C for 36 hours, and then filtered to obtain a solid product. The solid product was further dried at 120°C for 6 hours and calcined at 550°C for 6 hours to obtain TS-1-5 porous molecular sieve material.

[0221] Characterization of porous molecular sieve material TS-1-5:

[0222] XRD analysis showed that TS-1-5 molecular sieve has an MFI structure.

[0223] SEM results showed that the surface of TS-1-5 molecular sieve contained open pores with a size of not less than 15 nm.

[0224] TEM results show that the open pore size of the TS-1-5 molecular sieve is not less than 30 nm; no isolated hollow structures were observed in the molecular sieve grains.

[0225] The nitrogen adsorption-desorption characterization results showed that the nitrogen adsorption curve of TS-1-5 molecular sieve had three concave arcs, two of which were located at p / p0 less than 0.3 and one was located at p / p0 greater than 0.7; there were two hysteresis loops, the first of which was located in the range of relative pressure p / p0 less than 0.3 and the second of which was located in the range of relative pressure p / p0 greater than 0.45.

[0226] The chemical composition, specific surface area, and pore volume characterization results are shown in Table 1.

[0227] The cyclohexanone ammoniation reaction of porous molecular sieve material TS-1-5 was evaluated, and the results are shown in Table 1.

[0228] Example 6

[0229] This embodiment illustrates the preparation, characterization, and evaluation of the porous molecular sieve material TS-1-6 of the present invention.

[0230] The titanium-silicon molecular sieve obtained in Preparation Example 2 was mixed with polyquaternium-37 and water in a ratio of molecular sieve (molar): polyquaternium-37 (weight): water (weight) of 1:0.2:50. The mixture was treated at 145°C for 24 hours, and then filtered to obtain a solid product. The solid product was further dried at 120°C for 6 hours and calcined at 550°C for 6 hours to obtain TS-1-6 porous molecular sieve material.

[0231] Characterization of porous molecular sieve material TS-1-6:

[0232] XRD analysis showed that TS-1-6 molecular sieve has an MFI structure.

[0233] SEM results showed that the surface of TS-1-6 molecular sieve contained open pores with a size of not less than 18 nm.

[0234] TEM results show that the open pore size of the TS-1-6 molecular sieve is not less than 35 nm; no isolated hollow structures were observed in the molecular sieve grains.

[0235] The nitrogen adsorption-desorption characterization results showed that the nitrogen adsorption curve of TS-1-6 molecular sieve had three concave arcs, two of which were located at p / p0 less than 0.3 and one was located at p / p0 greater than 0.7; there were two hysteresis loops, the first of which was located in the range of relative pressure p / p0 less than 0.3 and the second of which was located in the range of relative pressure p / p0 greater than 0.45.

[0236] The chemical composition, specific surface area, and pore volume characterization results are shown in Table 1.

[0237] The cyclohexanone ammoniation reaction of porous molecular sieve material TS-1-6 was evaluated, and the results are shown in Table 1.

[0238] Comparative Example 3

[0239] This comparative example illustrates the characterization and evaluation of the all-silica molecular sieve S-1-D prepared by conventional methods.

[0240] Tetrapropyl ammonium hydroxide and water were mixed to obtain silica gel with a molar composition of SiO2:tetrapropyl ammonium hydroxide:water = 1:0.2:30. This silica gel was aged at 60℃ for 10 h, and then crystallized at 170℃ for 72 h. The crystallized product was then filtered, washed, dried at 120℃ for 6 h, and calcined at 550℃ for 6 h to obtain the all-silica molecular sieve comparative sample S-1-D.

[0241] Characterization of the all-silica molecular sieve comparative sample S-1-D:

[0242] XRD analysis showed that S-1-D is an MFI structure.

[0243] SEM results show that the S-1-D surface has no open pores. Figure 11 ).

[0244] TEM results show that S-1-D has a dense structure with no open mesopores or hollow structures. Figure 12 ).

[0245] Nitrogen adsorption-desorption characterization results showed that the nitrogen adsorption curve of STS-D molecular sieve exhibited two concave arcs, one located at p / p0 < 0.3 and the other at p / p0 > 0.7; a hysteresis loop was also observed at p / p0 > 0.8. Figure 13 ).

[0246] The chemical composition, specific surface area, and pore volume characterization results are shown in Table 1.

[0247] The cyclohexanone oxime gas-phase Beckmann rearrangement reaction of the all-silica molecular sieve comparative sample S-1-D was evaluated, and the results are shown in Table 1.

[0248] Example 7

[0249] This embodiment illustrates the preparation, characterization, and evaluation of the porous molecular sieve material S-1-1 of the present invention.

[0250] The all-silica molecular sieve obtained in Preparation Example 3 was mixed with polyquaternium-7 and water in a ratio of molecular sieve (molar): polyquaternium-7 (weight): water (weight) of 1:0.005:10. The mixture was treated at 180°C for 24 hours, and then filtered from the product to obtain a solid product. The solid product was further dried at 120°C for 6 hours and calcined at 550°C for 6 hours to obtain S-1-1 porous molecular sieve material.

[0251] Characterization of porous molecular sieve material S-1-1:

[0252] XRD analysis showed that the S-1-1 molecular sieve has an MFI structure.

[0253] SEM results showed that the surface of the S-1-1 molecular sieve contained open pores with a size of not less than 20 nm. Figure 14 ).

[0254] TEM results show that the open pore size on the surface of the S-1-1 molecular sieve is not less than 35 nm; no isolated hollow structures were observed in the molecular sieve grains.

[0255] Nitrogen adsorption-desorption characterization results showed that the nitrogen adsorption curve of S-1-1 molecular sieve exhibited three concave arcs, two of which were located at p / p0 < 0.3, and one located at p / p0 > 0.7; two hysteresis loops were also observed, with the first hysteresis loop located in the range where the relative pressure p / p0 was less than 0.3, and the second hysteresis loop located in the range where the relative pressure p / p0 was greater than 0.45. Figure 15 ).

[0256] The chemical composition, specific surface area, and pore volume characterization results are shown in Table 1.

[0257] The porous molecular sieve material S-1-1 was evaluated by the gas-phase Beckmann rearrangement reaction of cyclohexanone oxime, and the results are shown in Table 1.

[0258] Example 8

[0259] This embodiment illustrates the preparation, characterization, and evaluation of the porous molecular sieve material S-1-2 of the present invention.

[0260] The all-silica molecular sieve obtained in Preparation Example 3 was mixed with polyquaternium-2 and water in a ratio of molecular sieve (molar): polyquaternium-2 (weight): water (weight) of 1:0.2:50. The mixture was treated at 170°C for 48 hours, and then filtered to obtain a solid product. The solid product was further dried at 120°C for 6 hours and calcined at 550°C for 6 hours to obtain S-1-2 porous molecular sieve material.

[0261] Characterization of porous molecular sieve material S-1-2:

[0262] XRD analysis showed that the S-1-2 molecular sieve has an MFI structure.

[0263] SEM results showed that open pores with a size of not less than 15 nm existed on the surface of the S-1-2 molecular sieve.

[0264] TEM results show that the open pore size of the S-1-2 molecular sieve is not less than 30 nm; no isolated hollow structures were observed in the molecular sieve grains.

[0265] The nitrogen adsorption-desorption characterization results showed that the nitrogen adsorption curve of S-1-2 molecular sieve had three concave arcs, two of which were located at p / p0 less than 0.3 and one was located at p / p0 greater than 0.7; there were two hysteresis loops, the first of which was located in the range of relative pressure p / p0 less than 0.3 and the second of which was located in the range of relative pressure p / p0 greater than 0.45.

[0266] The chemical composition, specific surface area, and pore volume characterization results are shown in Table 1.

[0267] The porous molecular sieve material S-1-2 was evaluated by the gas-phase Beckmann rearrangement reaction of cyclohexanone oxime, and the results are shown in Table 1.

[0268] Example 9

[0269] This embodiment illustrates the preparation, characterization, and evaluation of the porous molecular sieve material S-1-3 of the present invention.

[0270] The all-silica molecular sieve obtained in Preparation Example 3 was mixed with polyquaternium-32 and water in a ratio of molecular sieve (moles): polyquaternium-32 (weight): water (weight): ammonium carbonate of 1:0.05:15:0.03. The mixture was treated at 170°C for 12 hours, and then filtered to obtain a solid product. The solid product was further dried at 120°C for 6 hours and calcined at 550°C for 6 hours to obtain S-1-3 porous molecular sieve material.

[0271] Characterization of S-1-3 molecular sieve:

[0272] XRD analysis showed that the S-1-3 molecular sieve has an MFI structure.

[0273] SEM results showed that open pores with a size of not less than 30 nm existed on the surface of the S-1-3 molecular sieve.

[0274] TEM results show that the open pore size of the S-1-3 molecular sieve is not less than 40 nm; no isolated hollow structures were observed in the molecular sieve grains.

[0275] The nitrogen adsorption-desorption characterization results showed that the nitrogen adsorption curve of S-1-3 molecular sieve had three concave arcs, two of which were located at p / p0 less than 0.3 and one was located at p / p0 greater than 0.7; there were two hysteresis loops, the first of which was located in the range of relative pressure p / p0 less than 0.3 and the second of which was located in the range of relative pressure p / p0 greater than 0.45.

[0276] The chemical composition, specific surface area, and pore volume characterization results are shown in Table 1.

[0277] The porous molecular sieve material S-1-3 was evaluated by the gas-phase Beckmann rearrangement reaction of cyclohexanone oxime, and the results are shown in Table 1.

[0278] Comparative Example 4

[0279] This comparative example illustrates the characterization and evaluation of Sn-MEL-D molecular sieves prepared by conventional methods.

[0280] Tetraethyl orthosilicate, stannous chloride, tetrapropylammonium hydroxide, and water were mixed and treated at 60°C for 12 h to obtain a sol with a molar composition of SiO2:SnO2:tetrapropylammonium hydroxide:water = 1:0.02:0.2:20. This sol was then crystallized at 170°C for 72 h. Finally, the solid product was obtained by filtration from the slurry, and further dried at 120°C for 6 h and calcined at 550°C for 6 h to obtain the molecular sieve comparison sample Sn-MEL-D.

[0281] Characterization of the molecular sieve comparison sample Sn-MEL-D:

[0282] XRD analysis showed that Sn-MEL-D molecular sieve has a MEL structure.

[0283] SEM results showed that the surface of Sn-MEL-D molecular sieve had no open pores. Figure 16 ).

[0284] TEM results show that Sn-MEL-D molecular sieves have a dense structure with no open mesopores or hollow structures.

[0285] Nitrogen adsorption-desorption characterization results showed that the nitrogen adsorption curve of Sn-MEL-D molecular sieve had two concave arcs, one located at p / p0 < 0.3 and the other at p / p0 > 0.7; a hysteresis loop was present at p / p0 > 0.8. Figure 17 The chemical composition, specific surface area, and pore volume characterization results are shown in Table 1.

[0286] The cyclohexanone BV oxidation reaction of the molecular sieve comparison sample Sn-MEL-D was evaluated, and the results are shown in Table 1.

[0287] Example 10

[0288] This embodiment illustrates the preparation, characterization, and evaluation of the porous molecular sieve material Sn-MEL of the present invention.

[0289] The tin-silicon molecular sieve obtained in Preparation Example 3 was mixed with polyquaternium-6 and water in a ratio of molecular sieve (molar): polyquaternium-6 (weight): water (weight) of 1:0.003:5. The mixture was treated at 140°C for 6 hours, and then filtered to obtain a solid product. The solid product was further dried at 120°C for 6 hours and calcined at 550°C for 6 hours to obtain Sn-MEL porous molecular sieve material.

[0290] Characterization of the porous molecular sieve material Sn-MEL:

[0291] XRD analysis showed that the Sn-MEL molecular sieve has a MEL structure.

[0292] SEM results showed that open pores with a size of not less than 10 nm existed on the surface of the Sn-MEL molecular sieve. Figure 18 ).

[0293] TEM results show that the open pore size of the Sn-MEL molecular sieve is not less than 20 nm; no hollow structure was observed in the molecular sieve grains.

[0294] Nitrogen adsorption-desorption characterization results showed that the nitrogen adsorption curve of Sn-MEL molecular sieve exhibited three concave arcs, two of which were located at p / p0 < 0.3, and one at p / p0 > 0.7; two hysteresis loops were also observed, with the first hysteresis loop located in the range where the relative pressure p / p0 was less than 0.3, and the second hysteresis loop located in the range where the relative pressure p / p0 was greater than 0.45. Figure 19 ).

[0295] The chemical composition, specific surface area, and pore volume characterization results are shown in Table 1.

[0296] The cyclohexanone BV oxidation reaction of the porous molecular sieve material Sn-MEL was evaluated, and the results are shown in Table 1.

[0297] Comparative Example 5

[0298] This comparative example illustrates the characterization and evaluation of Zr-MFI-D molecular sieves prepared by conventional methods.

[0299] Tetraethyl orthosilicate, zirconium propoxide, tetrapropylammonium hydroxide, and water were mixed and treated at 60 °C for 12 h to obtain a sol with a molar composition of SiO2:ZrO2:tetrapropylammonium hydroxide:water = 1:0.02:0.2:20. This sol was then crystallized at 170 °C for 72 h. The solid product was obtained by filtration from the slurry and further dried at 120 °C for 6 h and calcined at 550 °C for 6 h to obtain the molecular sieve comparison sample Zr-MFI-D.

[0300] Characterization of the molecular sieve comparison sample Zr-MFI-D:

[0301] XRD analysis showed that the Zr-MFI-D molecular sieve has an MFI structure.

[0302] SEM results showed that the surface of Zr-MFI-D molecular sieve had no open pores. Figure 20 ).

[0303] TEM results show that Zr-MFI-D molecular sieves have a dense structure with no open mesopores or hollow structures.

[0304] Nitrogen adsorption-desorption characterization results showed that the nitrogen adsorption curve of Zr-MFI-D molecular sieve had two concave arcs, one located at p / p0 < 0.3 and the other at p / p0 > 0.7; a hysteresis loop was present at p / p0 > 0.45. Figure 21 The chemical composition, specific surface area, and pore volume characterization results are shown in Table 1.

[0305] The levulinic acid MPV reaction of the molecular sieve comparison sample Zr-MFI-D was evaluated, and the results are shown in Table 1.

[0306] Example 11

[0307] This embodiment illustrates the preparation, characterization, and evaluation of the porous molecular sieve material Zr-MFI of the present invention.

[0308] The zirconium silicate molecular sieve obtained in Preparation Example 4 was mixed with polyquaternium-7 and water in a ratio of molecular sieve (molar): polyquaternium-7 (weight): water (weight) of 1:0.003:5. The mixture was treated at 140°C for 6 hours, and then filtered to obtain a solid product. The solid product was further dried at 120°C for 6 hours and calcined at 550°C for 6 hours to obtain Zr-MFI porous molecular sieve material.

[0309] Characterization of porous molecular sieve material Zr-MFI:

[0310] XRD analysis showed that the Zr-MFI molecular sieve has an MFI structure.

[0311] SEM results showed that open pores with a size of not less than 10 nm existed on the surface of the Zr-MFI molecular sieve. Figure 22 ).

[0312] TEM results show that the open pore size of the Zr-MFI molecular sieve is not less than 20 nm; no hollow structure was observed in the molecular sieve grains.

[0313] Nitrogen adsorption-desorption characterization results showed that the nitrogen adsorption curve of Zr-MFI molecular sieve exhibited three concave arcs, two of which were located at p / p0 < 0.3, and one at p / p0 > 0.7; two hysteresis loops were also observed, with the first hysteresis loop located in the range where the relative pressure p / p0 was less than 0.3, and the second hysteresis loop located in the range where the relative pressure p / p0 was greater than 0.45. Figure 23 ).

[0314] The chemical composition, specific surface area, and pore volume characterization results are shown in Table 1.

[0315] The levulinic acid MPV reaction of porous molecular sieve material Zr-MFI was evaluated, and the results are shown in Table 1.

[0316] Table 1

[0317]

[0318] As can be seen from Examples 1-10 and Comparative Examples 1-5, the low-temperature nitrogen adsorption isotherm curves of the porous molecular sieve material of the present invention exhibit at least three concave arcs and two hysteresis loops. The molecular sieve has open pores extending from the surface inward, and the BET specific surface area is 350-460 m². 2 / g, micropore volume is 0.15-0.19cm³ 3 / g, with a mesopore volume of 0.1-0.15 cm³ / g. The porous molecular sieve material preparation method provided by this invention is simple to operate and easy to implement. Due to the formation of a new pore structure, the reaction conversion rate and product selectivity (yield) are superior to those of molecular sieves with conventional pore structures.

[0319] The preferred embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the specific details of the above embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all fall within the protection scope of the present invention.

[0320] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not describe the various possible combinations separately.

[0321] Furthermore, various different embodiments of the present invention can be combined in any way, as long as they do not violate the spirit of the present invention, they should also be regarded as the content disclosed by the present invention.

Claims

1. A porous molecular sieve material, characterized in that, Its low-temperature nitrogen adsorption isotherm curve contains at least three concave arcs and at least two adsorption-desorption hysteresis loops, including a first hysteresis loop and a second hysteresis loop. At least two concave arcs are located at a relative pressure p / p0 < 0.3, and at least one concave arc is located at a relative pressure p / p0 > 0.

7. The first hysteresis loop is located in the range where the relative pressure p / p0 is less than 0.3, and the second hysteresis loop is located in the range where the relative pressure p / p0 is greater than 0.

45. Characterized by SEM, its surface has at least one surface pore with a maximum radial dimension of not less than 5 nm. This surface pore extends into the interior of the porous molecular sieve material to form open pores. Characterized by TEM, the pore size of the open pores is not less than 10 nm. Some of the molecular sieve grains have isolated hollow structures.

2. The porous molecular sieve material according to claim 1, characterized in that, The zeolite contains silicon as the first framework element and further contains one or more elements selected from C, Ge, Sn, Pb, Ti, Zr, Hf, B, Al, and Ga as the second framework element.

3. The porous molecular sieve material according to claim 2, characterized in that, The second skeleton element is selected from one or more of Sn, Ti, and Zr.

4. The porous molecular sieve material according to claim 2 or 3, characterized in that, The molar ratio of the first skeleton element to the second skeleton element is 1:(0.0001-1).

5. The porous molecular sieve material according to claim 4, characterized in that, The molar ratio of the first skeleton element to the second skeleton element is 1:(0.001-0.4).

6. The porous molecular sieve material according to claim 1, characterized in that, Characterized by SEM, its surface has at least one surface hole with a maximum radial dimension of not less than 10 nm.

7. The porous molecular sieve material according to claim 1, characterized in that, Characterized by SEM, its surface has at least one surface hole with a maximum radial dimension of not less than 20 nm.

8. The porous molecular sieve material according to claim 1, characterized in that, Characterized by TEM, the pore size of the open hole is not less than 20 nm.

9. The porous molecular sieve material according to claim 1, characterized in that, Characterized by TEM, the pore size of the open hole is not less than 40 nm.

10. The porous molecular sieve material according to any one of claims 1-9, characterized in that, Its crystal structure is selected from one or more of BEA, MFI, MEL, MWW, and SVR.

11. The porous molecular sieve material according to claim 1, characterized in that, Its BET specific surface area, as determined by low-temperature nitrogen adsorption-desorption characterization, is 350-460 m². 2 / g, micropore volume is 0.15-0.19cm³ 3 / g, mesopore volume is 0.1-0.15cm³ 3 / g.

12. A method for preparing the porous molecular sieve material according to claim 1, characterized in that, Molecular sieves containing silicon as the first framework element are mixed with polyquaternary ammonium base, water, and optionally added small molecule nitrogen-containing basic compounds, and treated at 100-200℃ for 1-72 hours. At least a portion of the solid product is separated from the treated product and then dried and calcined.

13. The method according to claim 12, characterized in that, The polyquaternary ammonium base has an average degree of polymerization of 10-100,000, and is obtained by hydroxyl exchange of polyquaternary ammonium salt.

14. The method according to claim 13, characterized in that, The polyquaternary ammonium base is obtained by hydroxyl exchange of polyquaternary ammonium salt-2, polyquaternary ammonium salt-6, polyquaternary ammonium salt-7, polyquaternary ammonium salt-22, polyquaternary ammonium salt-32, polyquaternary ammonium salt-37, polyquaternary ammonium salt-39, and polyquaternary ammonium salt-47.

15. The method according to claim 12, characterized in that, The small molecule nitrogen-containing basic compound is selected from one or more organic ammonium salts and inorganic ammonium salts with no more than 15 carbon atoms.

16. The method according to claim 15, wherein, The organic ammonium salt is a straight-chain carboxylic acid ammonium salt, a cyclic carboxylic acid ammonium salt, or an aromatic carboxylic acid ammonium salt with no more than 15 carbon atoms.

17. The method according to claim 16, characterized in that, The organic ammonium salt has no more than 12 carbon atoms.

18. The method according to claim 17, characterized in that, The organic ammonium salt has no more than 6 carbon atoms.

19. The method according to claim 17, characterized in that, The organic ammonium salt is one or more of the following: ammonium formate, ammonium acetate, ammonium propionate, ammonium butyrate, ammonium valerate, ammonium cyclovalerate, ammonium hexanoate, and ammonium hexenoate.

20. The method according to claim 15, characterized in that, The inorganic ammonium salt is one or more of the following: ammonium nitrate, ammonium phosphate, diammonium hydrogen phosphate, ammonium dihydrogen phosphate, ammonium sulfate, ammonium bisulfate, ammonium sulfite, ammonium bisulfite, ammonium chloride, ammonium bromide, ammonium fluoride, ammonium carbonate, and ammonium bicarbonate.

21. The method according to claim 12, characterized in that, In the mixture of the molecular sieve containing silicon as the first framework element, polyquaternary ammonium base, water, and optional small molecule nitrogen-containing alkaline compound, the ratio of the molecular sieve containing silicon as the first framework element to the polyquaternary ammonium base, water, and optional small molecule nitrogen-containing alkaline compound is 1:(0.001-0.5):(5-100):(0-0.3), wherein the molecular sieve containing silicon as the first framework element is measured in molar amounts of silicon dioxide, the polyquaternary ammonium base is measured in weight, the water is measured in weight, and the small molecule nitrogen-containing alkaline compound is measured in molar amounts.

22. The method according to claim 12, characterized in that, The preparation process is repeated 1-10 times.

23. The method according to claim 12, characterized in that, The molecular sieve containing silicon as the first framework element does not contain any other four-coordinate framework elements. The molecular sieve containing silicon as the first framework element is prepared by the following method: a silicon source, a quaternary ammonium base, and water are mixed to obtain a first mixture, and aged at a temperature of 5-120°C for 0.5-24 hours to obtain a sol. The sol is then crystallized at a temperature of 100-200°C for 2-168 hours, and at least a portion of the product is separated from it. After drying and calcination, at least a portion of the molecular sieve is obtained.

24. The method according to claim 12, characterized in that, The molecular sieve containing silicon as the first framework element also contains a second framework element, which is selected from one or more of C, Ge, Sn, Pb, Ti, Zr, Hf, B, Al, and Ga. The molar ratio of silicon to the second framework element is 1:(0.001-1). The molecular sieve containing silicon as the first framework element is prepared by the following method: a silicon source, a second framework element source, a quaternary ammonium base, and water are mixed to obtain a first mixture, which is aged at a temperature of 5-120°C for 0.5-24 hours to obtain a sol. The sol is then crystallized at a temperature of 100-200°C for 2-168 hours, and at least a portion of the product is separated from it. After drying and calcination, at least a portion of the molecular sieve is obtained.

25. The method according to claim 24, characterized in that, The second framework element is selected from one or more of Sn, Ti, and Zr, and the molar ratio of silicon to the second framework element is 1:(0.0001-1).

26. The method according to claim 23 or 24, characterized in that, The silicon source is a monodisperse silicon source and / or an aggregated silicon source; the monodisperse silicon source is tetraalkoxysilane, and the aggregated silicon source is selected from silica gel, silica sol, and silica fume.

27. The method according to claim 26, characterized in that, The silicon source is a mixture of monodisperse silicon source and aggregated silicon source, with a molar ratio of monodisperse silicon source to aggregated silicon source of 1:(0.1-10), and the aggregated silicon source is calculated as silicon dioxide.

28. The method according to claim 27, characterized in that, The molar ratio of monodisperse silicon sources to aggregated silicon sources is 1:(0.5-7).

29. The method according to claim 28, characterized in that, The molar ratio of monodisperse silicon sources to aggregated silicon sources is 1:(1-5).

30. The method according to claim 29, characterized in that, The molar ratio of monodisperse silicon sources to aggregated silicon sources is 1:(2-4).

31. The method according to claim 24, characterized in that, When the second skeleton element is C, the second skeleton element source has the structure A1A2A3Si-A4-SiA5A6A7, wherein A1, A2, A3, A5, A6, and A7 are each independently C1-C10 alkoxy or halogen groups with or without substitution, and A4 is a C1-C3 alkyl group.

32. The method according to claim 31, characterized in that, A1, A2, A3, A5, A6, and A7 are each independently a C1-C8 alkoxy or halogen group, and A4 is a C1-C2 alkyl group.

33. The method according to claim 31, characterized in that, A1, A2, A3, A5, A6, and A7 are each independently a C1-C3 alkoxy or halogen group, and A4 is a C1 alkyl group.

34. The method according to claim 31, characterized in that, When the second skeleton element is C, the source of the second skeleton element is one or more of bis(trimethoxysilyl)methane, bis(triethoxysilyl)methane, bis(tripropoxysilyl)methane, bis(trichlorosilyl)methane, and bis(diethoxychlorosilyl)methane.

35. The method according to claim 24, characterized in that, When the second skeleton element is Ge, the source of the second skeleton element is one or more of germanium monoxide, germanium dioxide, germanium tetrafluoride, germanium tetrachloride, germanium tetrabromide, germanium tetraiodide, germanium sulfide, tetramethyl germanium, tetraethyl germanium, tetrapropyl germanium, tetrabutyl germanium, methylgermanane, ethylgermanane, propylgermanane, and butylgermanane.

36. The method according to claim 24, characterized in that, When the second skeleton element is Sn, the source of the second skeleton element is one or more of tin dioxide, stannous oxide, stannous chloride, stannous trichloride, stannous tetrachloride, potassium stannate, sodium stannate, metastannic acid, stannic acid, tetramethyltin, tetraethyltin, tetrapropyltin, and tetrabutyltin.

37. The method according to claim 24, characterized in that, When the second skeleton element is Pb, the source of the second skeleton element is one or more of lead oxide, lead chloride, lead nitrate, lead sulfate, and lead acetate.

38. The method according to claim 24, characterized in that, When the second framework element is Ti, the source of the second framework element is at least one of titanium tetraalkoxy, titanium tetrachloride, titanium trichloride, titanium sulfate, fluorotitanic acid, titanium dichlorodicenocene, and titanium nitrate.

39. The method according to claim 24, characterized in that, When the second framework element is Ti, the source of the second framework element is at least one of tetraethyl titanate, tetrapropyl titanate, and tetrabutyl titanate.

40. The method according to claim 24, characterized in that, When the second skeleton element is Zr, the source of the second skeleton element is one or more of zirconium tetrachloride, zirconium trichloride, zirconium oxychloride, zirconium oxysulfate, zirconium nitrate, zirconium acetate, and zirconium tetraalkoxy.

41. The method according to claim 24, characterized in that, When the second skeleton element is Hf, the source of the second skeleton element is one or more of hafnium oxide, hafnium tetrachloride, hafnium hydroxide, hafnium carbide, and hafnium boride.

42. The method according to claim 24, characterized in that, When the second skeleton element is B, the source of the second skeleton element is one or more of boron oxide, boric acid, borax, alkylboron compounds, and alkoxyboron compounds.

43. The method according to claim 24, characterized in that, When the second skeleton element is Al, the source of the second skeleton element is one or more of the following: aluminum oxide, aluminum trichloride, aluminum sulfate, aluminum nitrate, aluminum phosphate, sodium aluminate, aluminum acetate, alkyl aluminum compounds, and alkoxy aluminum compounds.

44. The method according to claim 24, characterized in that, When the second framework element is Ga, the source of the second framework element is one or more of gallium oxide, gallium chloride, gallium sulfate, gallium nitrate, gallium phosphate, sodium gallate, gallium acetate, alkyl gallium compounds, and alkoxy gallium compounds.

45. The method according to claim 23 or 24, characterized in that, The quaternary ammonium base has R1R2R3R4N + OH - The structure consists of R1, R2, R3, and R4, which are independent alkyl or alkenyl groups with 2-5 carbon atoms each.

46. ​​The method according to claim 45, characterized in that, R1, R2, R3, and R4 are each independent alkyl or alkenyl groups with 3 carbon atoms.

47. The method according to claim 23 or 24, characterized in that, The molar ratio of silicon source, quaternary ammonium base, and water is 1:(0.05-0.3):(5-60).

48. The method according to claim 23 or 24, characterized in that, Before crystallization, a material with a crystalline structure is added, wherein the weight ratio of the crystalline material to the silicon source (based on SiO2) is (0.001-2):

1.

49. The method according to claim 48, characterized in that, The material of the crystal structure has an MFI structure, and the material of the crystal structure contains Si and O, or the material of the crystal structure contains Si, O and one or more of the elements C, Si, Ge, Sn, Pb, Ti, Zr, Hf, B, Al, and Ga.

50. Porous molecular sieve materials prepared by the method according to any one of claims 12-49.

51. A method for applying a porous molecular sieve material, characterized in that, The porous molecular sieve material containing any one of claims 1-11, 50 is used in adsorption processes, catalytic reactions, or as a support.

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