Aluminum-rich MCM-22 molecular sieve as well as preparation method and application thereof

Abstract

The invention relates to the technical field of MCM-22 molecular sieve preparation, and provides an aluminum-rich MCM-22 molecular sieve as well as a preparation method and application thereof. The molar ratio of silicon atoms to aluminum atoms in the MCM-22 molecular sieve is less than 10, and the relative crystallinity is greater than 80%. According to the aluminum-rich MCM-22 molecular sieve provided by the invention, the silicon-aluminum powder prepared by adopting a special process is used as a silicon source and an aluminum source, and the control on the skeleton composition of the nano MCM-22 molecular sieve can be realized, so that the microporous crystallinity of the MCM-22 molecular sieve is enhanced, the acid distribution of the MCM-22 molecular sieve is optimized, and the aromatic hydrocarbon conversion performance of the MCM-22 molecular sieve is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of MCM-22 molecular sieve preparation, and more specifically, to an aluminum-rich MCM-22 molecular sieve and a preparation method and application thereof. Background Art

[0002] MCM-22 molecular sieve is a molecular sieve with a unique pore structure developed by Mobil Corporation in the United States in 1990. It belongs to the MWW structure molecular sieve and has high thermal stability, high specific surface area and excellent adsorption capacity for water and small organic molecules. The basic structural unit of MCM-22 crystal is {4 3 5 6 6 3 {4 3}}, forming a space group of P6 / mmm or Cmmm. The structural model of MCM-22 crystals includes two independent pore systems, including a supercage formed by cylinders. Sine ten-ring mesh channel Leonowicz et al. confirmed the layered structure of MCM-22, with the layers connected by oxygen bridges. It has a two-dimensional sinusoidal cross-pore of ten-membered rings and a bowl-shaped twelve-membered ring semi-supercage structure on the surface (Science, 1994, 264: 1910-1913).

[0003] MCM-22 molecular sieve is a kind of catalytic material with great application prospects due to its unique pore structure and acid properties. At present, this molecular sieve has been industrially applied in alkylation reactions. It has also been widely studied in applications in the petrochemical field such as methanol to hydrocarbons, methane aromatization (MDA), Friedel-Crafts alkylation, toluene disproportionation, transalkylation, alkyl isomerization, n-hexane cracking to propylene, glycerol dehydration to acrolein, etc. It can also be used for the lightening of heavy oil, lightening of polycyclic aromatic hydrocarbons, and the synthesis of xylene isomerization.

[0004] MCM-22 molecular sieve has potential application prospects in aromatic hydrocarbon conversion. Peng Wu et al. used MCM-22 molecular sieve to catalyze the disproportionation of toluene to produce xylene, and pointed out that the disproportionation reaction mainly occurred in the super cage of MCM-22 molecular sieve at 473K-573K, and p-xylene was the initial product of the reaction. By eliminating aluminum in MCM-22 molecular sieve, the isomerization of p-xylene in the ten-membered ring channel was suppressed, and the selectivity of p-xylene was improved (Microporous Mesoperous Mater. 1998. 22: 343-356.). A. Corma et al. compared the catalytic effects of MCM-22, β and ZSM-5 molecular sieves in the alkylation of benzene with ethylene and propylene. MCM-22 molecular sieve showed higher activity, selectivity and better stability (Journal of Catalysis, 2000, 221 (1): 163-173.). In the reaction of ethylene and benzene to produce ethylbenzene, MCM-22 molecular sieve exhibits higher selectivity than β molecular sieve and Y molecular sieve, reducing the benzene / ethylene feed ratio and thus improving the benzene recovery efficiency (Applied Catalysis, A. General, 2001, 221(1 / 2):283-294.).

[0005] However, the silicon-aluminum atomic molar ratio (Si / Al) of MCM-22 molecular sieves prepared by existing methods is generally greater than 15, and it is difficult to prepare aluminum-rich MCM-22 molecular sieves with a low silicon-aluminum ratio. If the aluminum content in the MCM-22 molecular sieve framework can be increased, more abundant active acid catalytic centers can be provided, which will have great industrial application prospects. Summary of the invention

[0006] The purpose of the present invention is to provide an aluminum-rich MCM-22 molecular sieve and a preparation method and application thereof, so as to solve the technical problem that it is difficult to prepare a pure phase, high crystallinity, and low silicon-to-aluminum ratio MCM-22 molecular sieve in the prior art.

[0007] To achieve the above object, the technical solution adopted by the present invention is:

[0008] In a first aspect, the present invention provides a MCM-22 molecular sieve, wherein the silicon-aluminum atomic molar ratio (Si / Al) in the MCM-22 molecular sieve is less than 10 and the relative crystallinity is greater than 80%.

[0009] According to some embodiments of the present invention, the silicon to aluminum atomic molar ratio (Si / Al) in the MCM-22 molecular sieve is less than 7.5.

[0010] According to some embodiments of the present invention, the acid strength of the MCM-22 molecular sieve is shown as a desorption peak temperature of 200-350° C. in temperature-programmed ammonia desorption (NH 3 -TPD).

[0011] According to some embodiments of the present invention, the acid strength of the MCM-22 molecular sieve is shown as a desorption peak temperature of 300-350° C. in temperature-programmed ammonia desorption (NH 3 -TPD).

[0012] In order to understand the acidity of solid acid catalysis, ammonia temperature-programmed desorption (NH3-TPD) is usually used for characterization. For example, it can be measured on an Altamira AMI-3300 chemical adsorption instrument produced by Micrometrics Instruments, Inc., USA. The obtained temperature-programmed ammonia desorption curve has characteristic peaks at different desorption temperatures, corresponding to different acid strengths. The higher the desorption temperature corresponding to the characteristic peak, the greater the acid strength.

[0013] According to some embodiments of the present invention, in the MCM-22 molecular sieve, the content of framework aluminum accounts for more than 60 wt % of the total aluminum.

[0014] According to some embodiments of the present invention, in the MCM-22 molecular sieve, the content of framework aluminum accounts for more than 80 wt % of the total aluminum.

[0015] According to some embodiments of the present invention, the specific surface area S of the MCM-22 molecular sieve is BET ≥400m 2 / g, micropore volume V micro ≥0.15cm 3 / g.

[0016] According to some embodiments of the present invention, the specific surface area S of the MCM-22 molecular sieve is BET ≥450m 2 / g, micropore volume V micro ≥0.19cm 3 / g.

[0017] The aluminum-rich MCM-22 molecular sieve provided by the present invention breaks through the existing silicon-aluminum ratio by effectively controlling the silicon-aluminum atomic composition of the layered molecular sieve framework, has the characteristics of high acid strength and good crystallinity, and realizes the improvement of the micropore diffusion, mass transfer and reaction performance of the MCM-22 molecular sieve.

[0018] In a second aspect, the present invention provides a method for preparing MCM-22 molecular sieve, comprising:

[0019] S1. dissolving silicon aluminum powder, an alkali source and a template agent R in a solvent to form a colloid; the silicon aluminum atomic molar ratio of the silicon aluminum powder is not less than 1 (such as 1 to ∞), preferably 2 to 500; the surface hydroxyl concentration of the silicon aluminum powder is not less than 20 μmol / g, preferably not less than 30 μmol / g;

[0020] S2. crystallizing the colloid obtained in step S1 to obtain the MCM-22 molecular sieve;

[0021] Optionally, the method further comprises S3. calcining the MCM-22 molecular sieve once, then performing ion exchange, and then performing a second calcination.

[0022] Different from conventionally synthesized MCM-22 molecular sieves, the present invention uses silicon-aluminum powder as silicon source and aluminum source to control the framework composition of the MCM-22 molecular sieve, thereby enhancing the microporous crystallinity of the MCM-22 molecular sieve and optimizing its acidity distribution.

[0023] According to some embodiments of the present invention, the surface hydroxyl concentration of the silicon aluminum powder is 20 to 60 μmol / g, preferably 30 to 60 μmol / g.

[0024] According to some embodiments of the present invention, the silicon aluminum powder is measured by solid nuclear magnetic resonance aluminum spectroscopy. 27 According to Al MAS NMR detection, the signal peak area of ​​hexacoordinated non-framework aluminum accounts for ≤50% of the total area of ​​all signal peaks, preferably ≤20%.

[0025] In the present invention, solid state NMR aluminum spectroscopy 27 The “total area of ​​all signal peaks” in the Al MAS NMR detection results refers to the sum of the signal peak area of ​​hexacoordinated non-framework aluminum and the signal peak area of ​​tetracoordinated framework aluminum.

[0026] According to some embodiments of the present invention, the silicon aluminum powder is measured by solid nuclear magnetic resonance aluminum spectroscopy. 27 There are two types of characteristic signals in the Al MAS NMR detection, which are signal peaks near δ=0 and near δ=40-80.

[0027] In the present invention, the signal peak near δ=0 represents the hexacoordinated non-framework aluminum of the silicon aluminum powder, and the signal peak near δ=40-80 represents the tetracoordinated framework aluminum of the silicon aluminum powder.

[0028] In the present invention, by solid state nuclear magnetic resonance aluminum spectrum 27 The results of Al MAS NMR detection indicate that in the silicon-aluminum powder, more than 50% of the aluminum atoms in the composition form a framework four-coordinate structure.

[0029] According to some embodiments of the present invention, the silicon aluminum powder is subjected to solid state nuclear magnetic resonance silicon spectroscopy. 29 Si MAS NMR detection, the presence of Q 3 Coordination and Q 4 The characteristic signal of coordination, and Q 3 Coordination and Q 4The ratio of the peak area of ​​the coordinated characteristic signal peak to the total area of ​​all signal peaks is ≥30%, preferably ≥60% (eg, 60-100%).

[0030] In the present invention, solid-state NMR silicon spectroscopy 29 The “total area of ​​all signal peaks” in Si MAS NMR test results refers to Q 1 The peak area of ​​the characteristic signal peak of coordination, Q 2 The peak area of ​​the characteristic signal peak of coordination, Q 3 The peak area and Q of the characteristic signal peak of coordination 4 The sum of the peak areas of the characteristic signal peaks of the coordination. 1 Coordination, Q 2 Coordination, Q 3 Coordination and Q 4 The difference in coordination lies in the number of -OH groups directly connected to Si. 1 Coordination refers to the direct connection between Si and 3 -OH groups, Q 2 Coordination refers to the direct connection between Si and two -OH groups, Q 3 Coordination refers to the direct connection between Si and one -OH group. 4 Coordination means that Si is not directly connected to -OH.

[0031] In the present invention, Q 3 The characteristic signal of coordination is around δ = -110 ~ -100, Q 4 The characteristic signal of coordination is around δ=-120~-110.

[0032] In the present invention, solid-state nuclear magnetic resonance silicon spectroscopy 29 The results of Si MAS NMR detection show that the corresponding proportion of Q 3 , Q 4 Coordination.

[0033] According to some embodiments of the present invention, the silicon aluminum powder is detected by ultraviolet Raman spectroscopy at a vibration frequency of 240 cm -1 There is a characteristic peak nearby; at the vibration frequency of 335cm -1 、400cm -1 or 480cm -1 There is at least one characteristic peak near the vibration frequency of 335cm -1 、400cm -1 or 480cm -1 There is at least one characteristic peak with a peak intensity greater than the vibration frequency 240cm -1 The peak intensity of the characteristic peaks near .

[0034] The present invention uses silicon aluminum powder with "structural memory effect". The silicon aluminum powder used in the present invention is detected to have structural units such as four-membered rings, five-membered rings or six-membered rings through UV-Raman Raman spectroscopy structural characterization, which is consistent with the TOT skeleton structural unit in the synthesized molecular sieve and other silicon-containing crystalline materials. Therefore, the silicon aluminum powder used in the present invention can be called silicon aluminum powder with structural memory effect.

[0035] According to the present invention, in the ultraviolet Raman spectrum of silicon aluminum powder, the vibration frequency is 240cm -1 The characteristic peaks near the 8-membered ring (8MR) represent the bending vibration signal of TOT in the silicon-containing 8-membered ring (TOT bending vibration). -1 In the characteristic region of the structural unit, the smaller rings correspond to higher vibration frequencies, not 240 cm -1 Among the characteristic peaks nearby, 335cm -1 、400cm -1 and 480cm -1 The characteristic peaks near the ring represent the bending vibration of TOT in the six-membered ring (6MR), five-membered ring (5MR) and four-membered ring (4MR) containing silicon, respectively. -1 、400cm -1 or 480cm -1 The presence of at least one characteristic peak nearby indicates the presence of at least one structural unit of 6MR, 5MR or 4MR. Vibration frequency 335cm -1 、400cm -1 or 480cm -1 The peak intensity of the characteristic peak near the vibration frequency is greater than 240cm -1 The peak intensity of the characteristic peak near φ indicates that the number of 6MR, 5MR or 4MR structural units in the silicon-aluminum powder is greater than the number of 8MR structural units.

[0036] As for the expression "near" in the above content, those skilled in the art will know that each characteristic peak (signal peak) usually has a displacement, so the position of the characteristic peak defined in the present invention may have deviations. -1 The nearby characteristic peak is at 450cm -1 ~500cm -1 However, the deviation represented by each characteristic peak (signal peak) can be determined by those skilled in the art.

[0037] According to some embodiments of the present invention, the specific surface area of ​​the silicon aluminum powder is 500 to 1200 m 2 / g.

[0038] According to some embodiments of the present invention, the pore volume of the silicon aluminum powder is 0.05 to 5 cm 3 / g.

[0039] According to some embodiments of the present invention, the method for preparing the silicon aluminum powder comprises the following steps:

[0040] S1, providing a mixed solution I containing a treatment reagent I and a solvent I; the treatment reagent I comprises a halogen-containing compound, preferably at least one selected from silicon tetrafluoride, silicon tetrachloride, ammonium fluoride, ammonium chloride, ammonium bromide, ammonium iodide, sodium fluoride, sodium chloride, sodium bromide, sodium iodide, hydrofluoric acid, hydrochloric acid and hydrobromic acid;

[0041] Providing a mixed solution II containing a treatment reagent II and a solvent II; the treatment reagent II includes an acidic reagent, preferably at least one selected from ammonium nitrate, nitric acid, ammonium fluoride, ammonium chloride, hydrochloric acid, ammonium bromide, perbromic acid, carbonic acid, acetic acid, phosphoric acid, oxalic acid, formic acid, acetic acid, citric acid, ammonium iodide, iodine-containing acid, hydrofluoric acid and hydrobromic acid;

[0042] S2, performing a first mixing process on the silicon-containing raw material and the mixed solution I to obtain a mixed solution III;

[0043] Performing a second mixing process on the aluminum-containing raw material and the mixed solution II to obtain a mixed solution IV;

[0044] S3, after mixing the mixed solution III with the mixed solution IV, sequentially subjecting the mixed solution to a standing treatment, a de-impurity treatment and a calcination treatment to obtain the silicon-aluminum powder.

[0045] According to some embodiments of the present invention, a small amount of alkaline substance may be added to the mixed solution I to further promote the activation of the silicon-containing raw material.

[0046] According to some embodiments of the present invention, the solvent I and solvent II are the same or different, and are independently selected from at least one of water, alcohols and ionic liquids; preferably selected from at least one of deionized water, methanol, ethanol, isopropanol, n-butanol, ethylene glycol, 1-butyl-3-methylimidazolium tetrafluoroborate and 1-butyl-3-methylimidazolium hexafluorophosphate ([BMIM]PF6).

[0047] According to some embodiments of the present invention, the silicon-containing raw material is selected from at least one of silicates (such as tetramethyl silicate TMOS, tetraethyl silicate TEOS or tetrapropyl silicate TPOS), isobutylene triethoxysilane, tetramethylsilane (Si(CH3)4, silicon tetrachloride, methyltrimethoxysilane (MTMS), trichlorosilane (SiHCl3), hexamethyldisilazane and hexamethyldisiloxane.

[0048] According to some embodiments of the present invention, the aluminum-containing raw material is selected from at least one of aluminum sulfate, aluminum chloride, aluminum nitrate, aluminum hydrogen phosphate, aluminum sol, pseudo-boehmite, alumina powder prepared by alcohol aluminum process, boehmite, α-alumina, β-alumina, γ-alumina and θ-alumina.

[0049] According to some embodiments of the present invention, the molar ratio of the treatment reagent I to SiO2 in the silicon-containing raw material (hereinafter referred to as the treatment reagent I / SiO2 molar ratio) is 0.0001 to 2:1, preferably 0.001 to 0.2:1.

[0050] According to some embodiments of the present invention, the molar ratio of the solvent I to SiO2 in the silicon-containing raw material (hereinafter referred to as the solvent I / SiO2 molar ratio) is 0.5 to 100:1, preferably 1 to 10:1.

[0051] According to some embodiments of the present invention, the mass ratio of the treatment reagent II to Al2O3 in the aluminum-containing raw material is 0.0001 to 2:1, preferably 0.001 to 0.25:1.

[0052] According to some embodiments of the present invention, in the aluminum-containing mixed solution II, the mass fraction of Al2O3 is 0.1% to 60%, preferably 1% to 31%.

[0053] According to some embodiments of the present invention, the conditions for the first mixing process include: a stirring speed of 0 to 5000 rpm, preferably 2 to 100 rpm; a temperature of 0 to 50° C., preferably 5 to 30° C. The mixing process is performed for 1 second to 10 hours.

[0054] According to some embodiments of the present invention, the conditions for performing the second mixing process include: a stirring speed of 0 to 5000 rpm, preferably 2 to 100 rpm; a temperature of 0 to 50° C., preferably 5 to 30° C. The mixing process is performed for 1 second to 10 hours.

[0055] According to some embodiments of the present invention, in step S3, the conditions for the static treatment include: a temperature of -30 to 50°C; and / or a time of 10 to 2000 min. The static treatment is completed by sealed curing at -30 to 50°C for 10 to 2000 min.

[0056] According to some embodiments of the present invention, the temperature of the impurity removal treatment is 20-100° C. The solvent and volatile substances are removed at 20-100° C. The impurity removal treatment method includes an oven, a muffle furnace / mesh belt kiln, an infrared lamp, irradiation, vacuum filtration, natural light exposure, etc.

[0057] According to some embodiments of the present invention, the conditions for the calcination treatment include: a temperature of 200 to 1200° C.; and a time of 0.1 to 100 h.

[0058] According to some embodiments of the present invention, the calcination conditions include: in the temperature range of 250 to 1100° C., at least two calcination temperatures are selected from low to high in an air atmosphere for 0.01 to 2 h, preferably 0.1 to 2 h.

[0059] According to some embodiments of the present invention, the calcination conditions include: performing the calcination at 250-350°C, 350-500°C, and 500-1100°C for 0.01-2h, preferably 0.1-2h.

[0060] In the present invention, the calcination treatment is used to remove the skeleton crystal water (the desorption temperature is usually ≥ 200°C under normal pressure), sublimable fluoride, sulfur or MoO x It can also completely decompose organic matter by high-temperature oxidation.

[0061] According to some embodiments of the present invention, in step S3, after the mixed liquid III is mixed with the mixed liquid IV, a sol-gel is obtained, and the sol-gel is then subjected to a standing treatment and a de-impurity treatment (removal of solvent and volatile substances) until a solid block is precipitated, and the solid is powdered to obtain an intermediate powder; the intermediate powder is calcined to obtain the silicon-aluminum powder.

[0062] The preparation method of the silicon-aluminum powder adopted in the present invention selects silane-based silicon-rich substances and aluminum-containing substances as initial raw materials, and uses halogen-containing compounds and acidic reagents as treating agents, respectively, to highlight the hydrolysis and mineralization of silicon species, to form rich surface silanol species, and to form H + The protons represented by are acted on alumina, and through a simple and controllable treatment method, the solvent is recovered and the gel is obtained, which is then purified by high-temperature calcination to obtain solid silicon-aluminum powder with structural memory effect.

[0063] According to some embodiments of the present invention, the alkali source includes alkali metal hydroxide and / or ammonia water; preferably, the alkali metal includes at least one of Li, Na, K, Ru, and Cs.

[0064] According to some embodiments of the present invention, the template R includes at least one of cycloheximide (HMI), piperidine, unequal tetraalkylammonium, N,N,N-trimethyl-1-adamantylammonium hydroxide, N,N,N-trimethyl-1-adamantylammonium bromide, pyridine, cyclopropylamine, cyclobutylamine, cyclooctylamine, and cyclohexylmethylamine.

[0065] In the present invention, non-equivalent tetraalkylammonium refers to quaternary ammonium with four alkyl groups that are not completely the same, such as monomethyltripropylammonium hydroxide, diethyldipropylammonium hydroxide, and the like.

[0066] According to some embodiments of the present invention, the solvent includes at least one of water, an alcohol solvent, and an imidazole-type ionic liquid; preferably, the solvent I includes at least one of deionized water, methanol, ethanol, isopropanol, ethylene glycol, glycerol, acetone, and n-butanol.

[0067] According to some embodiments of the present invention, the molar ratio of the alkali source to the silicon element in the silicon-aluminum powder is: OH - / Si=0.1~0.25.

[0068] According to some embodiments of the present invention, the molar ratio of the solvent to the silicon element in the silicon aluminum powder is: I / Si=5-50, for example, it can be 5, 8, 10, 12, 13, 15, 18, 20, 21, 23, 25, 29, 30, 35, 37, 40, 45, 48, 50, etc.

[0069] According to some embodiments of the present invention, the molar ratio of the template R to the silicon element in the silicon aluminum powder is: R / Si=0.01-0.95, for example, it can be 0.01, 0.05, 0.10, 0.15, 0.18, 0.25, 0.33, 0.40, 0.44, 0.50, 0.55, 0.60, 0.62, 0.63, 0.65, 0.70, 0.77, 0.82, 0.90, 0.95, etc.

[0070] According to some embodiments of the invention, the ion exchange comprises ammonium exchange.

[0071] According to some embodiments of the present invention, the ammonium exchange reagent includes at least one of ammonium nitrate, ammonium chloride, ammonium oxalate, and ammonium sulfate.

[0072] According to some embodiments of the present invention, the ammonium exchange is carried out at a temperature of 10 to 120° C. for 0.1 to 1000 h, preferably at a temperature of 50 to 80° C. for 0.5 to 5 h.

[0073] According to some embodiments of the present invention, the concentration of the aqueous solution of the ammonium exchange reagent is 0.01 to 5 mol / L.

[0074] According to some embodiments of the present invention, the volume mass ratio of the ammonium exchange reagent aqueous solution to the MCM-22 molecular sieve is 4-10 mL: 1 g.

[0075] According to some embodiments of the present invention, the number of ion exchanges is 1 to 20 times, preferably 2 to 6 times.

[0076] According to some embodiments of the present invention, after the ion exchange, filtering, washing and drying are first performed, and then a secondary calcination is performed; preferably, the drying temperature is 30 to 200° C. and the drying time is 0.1 to 1000 h.

[0077] According to some embodiments of the present invention, the crystallization stirring speed is 0 to 6000 rpm, the crystallization temperature is 80 to 200° C., and the crystallization time is 2 to 2000 hours.

[0078] According to some embodiments of the present invention, after the crystallization, the method further includes filtering, washing and drying steps; preferably, the drying temperature is 30 to 200° C. and the drying time is 0.1 to 1000 h.

[0079] According to some embodiments of the present invention, the primary calcination temperature is 200-980° C., preferably 400-650° C., more preferably 500-550° C.; the primary calcination time is 0.1-250 h, preferably 1-10 h.

[0080] According to some embodiments of the present invention, the temperature of the secondary calcination is 400-650° C., preferably 500-550° C.; the time of the secondary calcination is 1-10 h.

[0081] According to some embodiments of the present invention, the secondary calcination is carried out in a staged calcination manner, including: calcining at a temperature of 150-200°C for 0.5-3h, then calcining at a temperature of 250-350°C for 0.5-3h, then calcining at a temperature of 400-500°C for 0.5-3h, and finally calcining at a temperature of 200-900°C for 0.1-100h.

[0082] In a third aspect, the present invention provides a MCM-22 molecular sieve prepared by the preparation method described in the second aspect.

[0083] In a fourth aspect, the present invention provides use of the MCM-22 molecular sieve described in the first aspect or the MCM-22 molecular sieve described in the third aspect in aromatic hydrocarbon conversion.

[0084] According to some embodiments of the present invention, the weight space velocity of aromatics in the aromatics conversion is 0.01 to 50 h -1 , the hydrogen-to-oil molar ratio is 0-300.

[0085] The aluminum-rich MCM-22 molecular sieve provided by the present invention is a solid acid catalytic material with a unique structure, has a large specific surface area and a strong acidic external surface active center (equivalent to the acidity of the corresponding three-dimensional structure zeolite), and exhibits very excellent adsorption and catalytic performance for aromatic molecules, and can provide more acid sites for aromatic conversion. The aluminum-rich MCM-22 molecular sieve provided by the present invention is used as an acidic component in catalyzing aromatic conversion reactions, and exhibits excellent performance.

[0086] According to some embodiments of the present invention, the application includes application in an aromatic hydrocarbon dealkylation reaction, such as application in a trimethylolbenzene selective dealkylation reaction.

[0087] According to some embodiments of the present invention, the temperature of the trimethylbenzene selective dealkylation reaction is 250-650° C. and the pressure is 0-20 MPa.

[0088] In a fifth aspect, the present invention provides an aromatic hydrocarbon conversion catalyst, wherein the catalyst comprises the MCM-22 molecular sieve described in the first aspect or the MCM-22 molecular sieve described in the third aspect.

[0089] According to some embodiments of the present invention, the catalyst further comprises an active component.

[0090] According to some embodiments of the present invention, the active component includes at least one of Group IIIA alumina metals, Group IVA metals, Group VA metals, transition metals (including Groups IB to VIIB metals, and Group VIII metals).

[0091] According to some embodiments of the present invention, the active component is selected from at least one of Y, La, Ce, Pr, Nd, Fe, Co, and Ni.

[0092] According to some embodiments of the present invention, the catalyst comprises a reduction step prior to the reaction.

[0093] According to some embodiments of the present invention, the reduction is carried out by hydrogen reduction, wherein the hydrogen flow rate is 8 to 800 mL / min; during the reduction, the temperature is first increased to 100 to 280°C at a rate of 0.1 to 20°C / min and kept constant at this temperature for 0 to 48 hours, and then the temperature is increased to 300 to 750°C at a rate of 0.1 to 50°C / min and kept constant at this temperature for 0 to 48 hours.

[0094] The beneficial effects of the present invention are at least:

[0095] The aluminum-rich MCM-22 molecular sieve provided by the present invention uses silicon-aluminum powder prepared by a special process as a silicon source and an aluminum source, so as to control the skeleton composition of the nano MCM-22 molecular sieve, thereby enhancing the microporous crystallinity of the MCM-22 molecular sieve, optimizing its acidity distribution, and improving the aromatics conversion performance of the MCM-22 molecular sieve. BRIEF DESCRIPTION OF THE DRAWINGS

[0096] Figure 1 Fourier transform infrared spectra of the silicon aluminum powder SAJ01 prepared in Preparation Example 1 of the present invention and the comparative sample DBJ prepared in Comparative Preparation Example 1 in the hydroxyl region.

[0097] Figure 2 This is the skeleton Fourier transform infrared spectrum of the silicon aluminum powder SAJ01 prepared in Preparation Example 1 of the present invention.

[0098] Figure 3 This is a scanning electron microscope photograph (SEM) of the silicon aluminum powder SAJ01 prepared in Preparation Example 1 of the present invention.

[0099] Figure 4 The solid magic angle aluminum nuclear magnetic resonance spectrum of the silicon aluminum powder SAJ01 prepared in Preparation Example 1 of the present invention is ( 27 Al MASNMR).

[0100] Figure 5 This is the solid magic angle aluminum nuclear magnetic resonance spectrum of the comparative sample DBJ prepared in comparative preparation example 1 of the present invention ( 27 AlMAS NMR).

[0101] Figure 6 The solid magic angle silicon nuclear magnetic resonance spectrum of the silicon aluminum powder SAJ01 prepared in Preparation Example 1 of the present invention ( 29 Si MASNMR).

[0102] Figure 7 These are the low-temperature nitrogen adsorption-desorption curves of the silicon aluminum powders SAJ01 and SAJ02 prepared in Preparation Examples 1 and 2 of the present invention.

[0103] Figure 8 UV-Raman spectra of the silicon aluminum powder SAJ01 prepared in Preparation Example 1 of the present invention and the comparative sample DBJ prepared in Comparative Preparation Example 1 at 244 nm ultraviolet excitation light.

[0104] Fig. 9 This is the XRD spectrum of the aluminum-rich MCM-22 molecular sieve prepared in Example 1 of the present invention.

[0105] Fig.10 This is a SEM photograph of the aluminum-rich MCM-22 molecular sieve prepared in Example 1 of the present invention.

[0106] Fig.11 This is a HR-TEM photograph of the aluminum-rich MCM-22 molecular sieve prepared in Example 1 of the present invention. DETAILED DESCRIPTION

[0107] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention more clearly understood, the present invention is further described in detail below in conjunction with specific embodiments. It should be understood that the specific embodiments described herein are only used to explain this patent in detail and do not limit the scope of protection of the present invention in any way.

[0108] Unless otherwise defined, the technical terms used in the following examples have the same meanings as those generally understood by those skilled in the art to which the present invention belongs. The reagents used in the following examples, unless otherwise specified, are all conventional biochemical reagents; the raw materials, instruments and equipment used in the following examples, etc., can all be purchased on the market or can be obtained by existing methods; the reagent amounts, unless otherwise specified, are the reagent amounts used in conventional experimental operations; the experimental methods, unless otherwise specified, are all conventional methods.

[0109] In each embodiment and comparative example of the present invention, each performance data is tested according to the following test method:

[0110] (1) Surface hydroxyl concentration: The hydroxyl area of ​​the molecular sieve was analyzed and measured using a Nexus 670 Fourier transform infrared spectrometer (FT-IR) produced by Nicolet, USA. The test method is to take 50 mg of molecular sieve sample powder and press it into a thin sheet with a diameter of 1 cm, put it into a vacuum cell, vacuum dehydrate it at 450°C for 1.5 hours, and then test it after the temperature drops to room temperature.

[0111] (2) Fourier transform infrared spectrum of skeleton vibration area: The analysis and test were carried out using Nexus670 Fourier transform infrared spectrometer (FT-IR) produced by Nicolet Company of the United States, with a test resolution of 4 cm -1 , scanning times 32 times, test range 400~4000cm -1 The test method is to dilute the sample powder with KBr to a mass fraction of about 3%, grind and mix it evenly with a mortar, press it into a tablet, and then scan it.

[0112] (3) Solid-state magic angle nuclear magnetic resonance spectroscopy 29 Si MAS NMR and 27 Al MAS NMR test: using Bruker Avance III / WB-400 spectrometer nuclear magnetic resonance instrument. 27 Al MAS NMR test standard KAl(SO4)2.12H2O, rotation speed 12kHz, resonance frequency 79.50MHz, relaxation time 4s; 29 Si MAS NMR Test Standard Q8M8([(CH3)3SiO]8SiO 12 ), rotation speed 3kHz, resonance frequency 79.43MHz, relaxation time 60s.

[0113] (4) Specific surface area and pore volume: The Tristar 3000 specific surface analyzer produced by Micrometrics was used to perform low-temperature N2 adsorption-desorption analysis of the samples. The samples were pretreated with vacuum activation at 300°C for 6 h before testing, and the test temperature was -196°C. The specific surface area, pore volume and other pore structure data of the test samples were obtained by analyzing the isotherms.

[0114] (5) Raman spectroscopy analysis: The molecular sieve samples were analyzed by Raman spectroscopy using a Jobin-Yvon T6400 triplet ultraviolet-Raman spectrometer (UV-Raman) developed by the Dalian Institute of Physical Chemistry, with a resolution of 2 cm -1 , the excitation light source wavelength is 244nm.

[0115] (6) Dry basis mass fraction of silicon aluminum powder: The sample was analyzed by thermogravimetric TG-DTA analysis using a TGA Q500analyzer (test conditions: air atmosphere, heating rate 10°C / min).

[0116] (7) Phase analysis (XRD spectrum): measured using a Bruker D8Focus diffractometer with a graphite monochromator, a Cu target Kα ray source, a wavelength λ of 0.154 nm, a tube voltage of 40 kV, a tube current of 40 mA, and recording diffraction signals in the 2θ range of 3-90° (scanning speed of 2° / min).

[0117] (8) Scanning electron imaging (SEM) images: taken using a FEI Nova Nano SEM 450 microscope.

[0118] (9) Spherical aberration transmission imaging (TEM) photos: taken using a FEI Tecnai 20S-Twin microscope.

[0119] (10) The ammonia temperature-programmed desorption (NH3-TPD) curve signal information was collected using an Altamira AMI-3300 chemical adsorption instrument produced by Micrometrics.

[0120] In each embodiment and comparative example of the present invention, the polytetrafluoroethylene-lined pressure steel autoclave used was purchased from Shandong Yantai Muping Shuguang Precision Instrument Factory, with a specification of 100 mL; the rotary oven was purchased from a 200L space rotary oven produced by Beijing Creaser Company.

[0121] Preparation Example 1

[0122] Weigh 0.1g of sodium hydroxide and 0.4g of sodium fluoride, add them into 200ml of deionized water, stir and mix until dissolved evenly, then add 500g of methanol and place in a constant temperature water bath at 10°C; under stirring at 30rpm, take 520g of tetramethyl silicate (TMOS) and add it to the above solution, stir evenly; wherein the molar ratio of the treatment reagent I / SiO2 is 0.0026; the molar ratio of the solvent I / SiO2 is 7.3.

[0123] A certain amount of pseudo-boehmite was weighed according to the Si / Al atomic molar ratio of 35, and slurried with water to obtain a slurry with an Al2O3 mass content of 16%. Under stirring conditions of 25°C and 30rpm, hydrochloric acid was added at a hydrochloric acid / Al2O3 mass ratio of 0.05 and stirred evenly.

[0124] The aluminum liquid was quickly added to the silicon-containing material and mixed evenly, and then placed in a container in a constant temperature water bath at 10°C for 2 hours to obtain a sol-gel. The solvent methanol and water were evaporated in a vacuum at 55°C until a solid block was precipitated, and then the solid was taken out and powdered to obtain an intermediate powder. The temperature was then raised to 550°C at 3°C / min, and the intermediate powder was calcined at a constant temperature for 3 hours to obtain sample SAJ01.

[0125] The surface hydroxyl concentration of sample SAJ01 is 39 μmol / g silicon aluminum powder, and the specific surface area is S BET =620m 2 / g, pore volume = 0.55cm 3 / g.

[0126] Figure 1 In the FT-IR spectrum, 3580-3600, 3680-3700 and 3720-3730 cm -1 The characteristic vibration peaks nearby correspond to the bridge hydroxyl group, internal hydroxyl group and terminal hydroxyl group (external hydroxyl group), and the areas of the above characteristic peaks of the SAJ01 sample are larger, indicating that its hydroxyl group distribution is richer.

[0127] Figure 8 In the UV-Raman spectrum, the vibration frequency is less than 600cm -1 The structural unit characteristic area of ​​DBJ01 is only amorphous TOT at 240 cm -1 As the TOT bond angle decreases and the force constant increases, the active Al atoms activate and ionize the Si-O bonds, increase the skeleton flexibility and reduce the skeleton stress. The SAJ01 sample has a peak at 335cm -1 , especially 400cm -1 and 480cm -1 Signal peaks belonging to specific structural units appeared near the positions of 335cm -1 、400cm -1and 480cm -1 The characteristic peaks near the surface overlap partially. It can be seen that the vibration frequency is around 335cm -1 、400cm -1 and 480cm -1 The peak area of ​​the characteristic peak near 240 cm -1 The peak area of ​​the characteristic peak nearby.

[0128] Figure 2 In the FT-IR spectrum of sample SAJ01, the -1 The vibration peaks nearby correspond to silanols species.

[0129] Depend on Figure 3 From the scanning electron microscope photograph, it can be seen that the nanoparticles of sample SAJ01 are uniform in size and highly dispersed.

[0130] Depend on Figure 4 It can be seen that sample SAJ01 shows tetracoordinated framework aluminum (δ>50), and there is no obvious characteristic peak attributable to hexacoordinated non-framework aluminum at δ=0, indicating that more than 50% of the aluminum atoms in sample SAJ01 form framework tetracoordinates.

[0131] Depend on Figure 6 It can be seen that the sample SAJ01 has Q corresponding to (SiO)4Si species and (SiO)3Si(1Al) near the chemical shifts -115 and -111, respectively. 4 The strong signal vibration peak of the structural species; the broadened NMR vibration peak signal of the sample at -104 is attributed to the (SiO)3Si(OH) species in the molecular sieve (Q 3 ), indicating that there are a certain amount of coordination defect (SiO)3Si(OH) species, and there are no obvious silicon species with other coordination numbers.

[0132] Comparative Preparation Example 1

[0133] Weigh white carbon black and pseudo-boehmite, and stir them mechanically to make them uniform; wherein the Si / Al atomic molar ratio is 35.

[0134] The obtained silicon and aluminum oxides form a powder mixture, and the comparative sample is marked as DBJ01.

[0135] Figure 1 In the FT-IR spectrum, 3580-3600, 3680-3700 and 3720-3730 cm -1 The characteristic vibration peaks nearby correspond to the bridge hydroxyl group, internal hydroxyl group and terminal hydroxyl group (external hydroxyl group), respectively. The above characteristic peak areas of DBJ01 sample are all small, indicating that its surface hydroxyl distribution is not as rich as that of SAJ01.

[0136] Depend on Figure 5 It can be seen that sample DBJ01 has an obvious characteristic peak attributable to hexacoordinated non-framework aluminum near δ=0, indicating that in this sample, the framework coordination of aluminum atoms mainly comes from the mechanical mixing composition of pseudo-boehmite, which is dominated by amorphous hexacoordinated non-framework aluminum.

[0137] Figure 8 In the UV-Raman spectrum, the vibration frequency is less than 600cm -1 The structural unit characteristic area of ​​DBJ01 is only amorphous TOT at 240 cm -1 characteristic peaks.

[0138] Using the sample of this comparative example as the synthetic raw material of the molecular sieve is not conducive to the formation of molecular sieve supercages or 10-membered ring and 12-membered ring microporous channels, and is likely to lead to the formation of dense phase small-pore zeolite impurities. At the same time, the crystallinity of the product will be significantly lower than the crystallinity of the product synthesized using SAJ01 as the raw material under the same synthetic conditions.

[0139] Comparative Preparation Example 2

[0140] A certain amount of pseudo-boehmite and tetramethyl silicate (TMOS) were weighed according to a Si / Al atomic molar ratio of 35.

[0141] Pseudo-boehmite was slurried with water to obtain a slurry with an Al2O3 mass content of 16%. Under stirring conditions of 25°C and 30 rpm, hydrochloric acid was added at a hydrochloric acid / Al2O3 mass ratio of 0.05 and stirred evenly.

[0142] The aluminum liquid was quickly added to tetramethyl silicate (TMOS) and mixed evenly, and then placed in a container in a constant temperature water bath at 10°C for 2 hours to obtain a sol-gel, and the solvent methanol and water were evaporated in a vacuum at 55°C until a solid block was precipitated, and then the intermediate powder was obtained by powdering. The temperature was then raised to 550°C at a rate of 3°C / min, and the intermediate powder was calcined at a constant temperature for 3 hours to obtain the sample DBJ02.

[0143] The characteristic vibration peak areas in the FT-IR spectrum of sample DBJ02 are smaller than those of sample SAJ01. 29 Si MAS NMR solid state nuclear magnetic resonance test results show that Q 4 The vibration signal peak of the structural species is significantly weaker than that of the SAJ01 sample. In the UV-Raman spectrum, the amorphous TOT in the DBJ02 sample is at 240 cm -1 The characteristic peaks of the SAJ01 sample are significantly stronger than those of the SAJ01 sample.

[0144] Using the sample of this comparative example as the synthetic raw material of the molecular sieve is not conducive to the formation of molecular sieve supercages or 10-membered ring and 12-membered ring microporous channels, and is likely to lead to the formation of dense phase small-pore zeolite impurities. At the same time, the crystallinity of the product will be significantly lower than the crystallinity of the product synthesized using SAJ01 as the raw material under the same synthetic conditions.

[0145] Comparative Preparation Example 3

[0146] Weigh 0.1g of sodium hydroxide and 0.4g of sodium fluoride, add them to 200ml of deionized water, stir and mix until dissolved evenly, then add 500g of methanol and place in a constant temperature water bath at 10°C; under stirring at 30rpm, take 520g of tetramethyl silicate (TMOS) and add it to the above solution, stir evenly; wherein the molar ratio of the treatment reagent I / SiO2 is 0.0026; the molar ratio of the solvent I / SiO2 is 7.3.

[0147] A certain amount of pseudo-boehmite was weighed according to the Si / Al atomic molar ratio of 35, and slurried with water to obtain a slurry with an Al2O3 mass content of 16%.

[0148] The aluminum liquid was quickly added to the silicon-containing material and mixed evenly, and then placed in a container in a constant temperature water bath at 10°C for 2 hours to obtain a sol-gel. The solvent methanol and water were evaporated in a vacuum at 55°C until a solid block was precipitated, and then the solid was taken out and powdered to obtain an intermediate powder. The temperature was then raised to 550°C at a rate of 3°C / min, and the intermediate powder was calcined at a constant temperature for 3 hours to obtain sample DBJ03.

[0149] The characteristic vibration peak areas in the FT-IR spectrum of sample DBJ03 are smaller than those of sample SAJ01. 27 The results of Al MAS NMR solid state nuclear magnetic resonance test show that the characteristic peak of hexacoordinated non-framework aluminum in DBJ03 sample near δ = 0 is significantly stronger than that in SAJ01 sample. At the same time, the amorphous TOT in DBJ03 sample in UV-Raman spectrum is at 240 cm -1 The characteristic peaks of the SAJ01 sample are significantly stronger than those of the SAJ01 sample.

[0150] Using the sample of this comparative example as the synthetic raw material of the molecular sieve is not conducive to the formation of molecular sieve supercages or 10-membered ring and 12-membered ring microporous channels, and is likely to lead to the formation of dense phase small-pore zeolite impurities. At the same time, the crystallinity of the product will be significantly lower than the crystallinity of the product synthesized using SAJ01 as the raw material under the same synthetic conditions.

[0151] Comparative Preparation Example 4

[0152] Weigh 0.1 g of sodium hydroxide and add it to 200 ml of deionized water. After mixing and stirring to dissolve evenly, add 500 g of methanol and place in a constant temperature water bath at 10°C. Under stirring at 30 rpm, take 520 g of tetramethyl silicate (TMOS) and add it to the above solution and stir evenly.

[0153] A certain amount of pseudo-boehmite was weighed according to the Si / Al atomic molar ratio of 35. The pseudo-boehmite was slurried with water to obtain a slurry with a mass content of 16% Al2O3.

[0154] The aluminum liquid is quickly added to the silicon-containing material and mixed evenly. After precipitation is obtained, it is transferred to a container and placed in a constant temperature water bath at 10°C for 2 hours. Under stirring conditions of 30rpm, 0.4g of sodium fluoride is first added and stirred evenly, and then hydrochloric acid is added and stirred evenly. The mass ratio of hydrochloric acid / Al2O3 is 0.05. The solvent methanol and water are vacuum evaporated at 55°C until a solid block is precipitated, and the powder is taken out to obtain an intermediate powder. Then the temperature is raised to 550°C at 3°C / min, and the intermediate powder is constant temperature roasted for 3 hours to obtain sample DBJ04.

[0155] The characteristic vibration peak area in the FT-IR spectrum of sample DBJ04 is significantly smaller than that of sample SAJ01. 27 The results of Al MAS NMR solid state nuclear magnetic resonance test show that the characteristic peaks attributed to hexacoordinated non-framework aluminum appear in DBJ04 sample near δ = 0, which is significantly stronger than that in SAJ01 sample. 29 Si MAS NMR solid state nuclear magnetic resonance test results show that the Q 4 The vibration signal peak of the structural species is obviously weaker than that of the SAJ01 sample. In addition, the amorphous TOT in the DBJ04 sample has a peak at 240 cm -1 The characteristic peaks of the SAJ01 sample are significantly stronger than those of the SAJ01 sample.

[0156] Using the sample of this comparative example as the synthetic raw material of the molecular sieve is not conducive to the formation of molecular sieve supercages or 10-membered ring and 12-membered ring microporous channels, and is likely to lead to the formation of dense phase small-pore zeolite impurities. At the same time, the crystallinity of the product will be significantly lower than the crystallinity of the product synthesized using SAJ01 as the raw material under the same synthetic conditions.

[0157] Preparation Example 2

[0158] Weigh 0.2 g of sodium fluoride, add it to 180 ml of deionized water, mix and stir until dissolved evenly, then add 460 g of isopropanol, and place in a constant temperature water bath at 25°C; under stirring at 12 rpm, take 485 g of hexamethyldisilazane and add it to the above solution, stir evenly, wherein the molar ratio of the treatment reagent I / SiO2 is 0.0008; the molar ratio of the solvent I / SiO2 is 2.94.

[0159] A certain amount of aluminum sulfate was weighed according to the Si / Al atomic molar ratio of 4, and dissolved in water to obtain a solution with a 20% Al2O3 mass content. NH4F was added at a NH4F / Al2O3 mass ratio of 0.005 at 25°C and 30 rpm stirring conditions and stirred evenly;

[0160] The aluminum liquid was quickly added to the silicon-containing material and mixed evenly. The mixture was placed in a 30°C constant temperature water bath in a container and allowed to stand for 0.5 h to obtain a sol-gel. The solvent isopropanol and water were evaporated under vacuum at 70°C until a solid block was precipitated. The solid was taken out and powdered to obtain an intermediate powder. The temperature was then raised to 450°C at a rate of 1.5°C / min, and the intermediate powder was calcined at a constant temperature for 8 h. Sample SAJ02 was obtained.

[0161] After testing, the surface hydroxyl concentration of the sample is 26μmol / g silicon aluminum powder, and the specific surface area is S BET =550m 2 / g, pore volume = 1.05cm 3 / g, UV-Raman detected its vibration frequency at 335cm -1 、400cm -1 and 480cm -1 The peak areas of the characteristic peaks near 240 cm -1 The peak area of ​​the characteristic peak nearby.

[0162] Figure 7 The low-temperature nitrogen adsorption-desorption curves of the silicon aluminum powders SAJ01 and SAJ02 prepared in Preparation Examples 1 and 2 of the present invention are exemplarily shown, and the pore structure data such as BET specific surface area and pore volume of the test samples are obtained by analyzing the isotherms.

[0163] Preparation Example 3-12

[0164] The preparation methods of Preparation Examples 3 to 12 are basically the same as those of Preparation Example 1, except for the selection of different silicon-containing raw materials, aluminum-containing raw materials, treatment reagents and solvent I. The specific preparation conditions are shown in Table 1 below. The samples are marked as SAJ03 to SAJ12 in sequence, and the performance parameter information of the samples is shown in Table 2 below.

[0165]

[0166]

[0167] Preparation Example 13-22

[0168] The preparation methods of Preparation Examples 13 to 22 are basically the same as those of Preparation Example 2, except for the selection of different treatment reagent I / SiO2 molar ratios, solvent I / SiO2 molar ratios, treatment reagent II / Al2O3 mass ratios and the mass fraction of Al2O3 in the aluminum-containing mixed solution. The specific preparation conditions are shown in Table 3 below. The samples are marked as SAJ13 to SAJ22 in sequence, and the performance parameter information of the samples is shown in Table 4 below.

[0169]

[0170]

[0171]

[0172] Preparation Example 23-32

[0173] Preparation Examples 23 to 32 are basically the same as Preparation Examples 13 to 22 (i.e., Preparation Example 23 follows Preparation Example 13, Preparation Example 24 follows Preparation Example 14, and so on), the difference is that the calcination activation conditions are different. The specific preparation conditions are shown in Table 5. The obtained samples are marked as SAJ23 to SAJ32, and the performance parameter information of the samples is shown in Table 6 below.

[0174]

[0175]

[0176]

[0177] Example 1

[0178] An aluminum-rich MCM-22 molecular sieve, the preparation method is as follows:

[0179] The silicon aluminum powder SAJ01 and KOH prepared in Preparation Example 1 are dissolved in a methanol solution, and cycloheximide and piperidine (the molar ratio of HMI to piperidine is 2:1) are added, wherein the molar ratio of SAJ01 (in terms of silicon element), NaOH, (cycloheximide and piperidine) to deionized water is 1:0.18:0.63:25; after stirring evenly, a milky white gelling solution is obtained; the gelling solution is then charged into a polytetrafluoroethylene-lined pressure steel autoclave, and after pre-crystallization at a temperature of 90°C for 6 hours, it is placed in a rotary oven at a temperature of 150°C and a rotation speed of 20 rpm for further hydrothermal crystallization for 160 hours, and then cooled to room temperature with tap water. The obtained product is filtered, washed, dried in an oven at 100°C for 2 hours, and then roasted at 550°C for 3 hours, and cooled to obtain molecular sieve raw powder.

[0180] The molecular sieve raw powder was tested, among which the XRD test was shown in Fig. 9It can be seen that it is a pure phase MWW configuration with a relative crystallinity of 85%. SEM and TEM photos are shown in Fig.10 and Fig.11 The SEM test results show the layered morphology that MWW usually presents, and the clear lattice fringes in the TEM test results show that its micropore crystallinity is good. 27 The Al MAS NMR results show that 87wt% of the aluminum species are in a four-coordinated state. The Si / Al ratio of this sample is 7, and the specific surface area S BET 458m 2 / g, micropore volume V micro 0.19m 3 / g.

[0181] The molecular sieve powder and 1 mol / L ammonium chloride aqueous solution were mixed evenly at a solid (mass, g) to liquid (volume, mL) ratio of 1:6, and heated in a water bath to 65°C for 1 h for ion exchange; then filtered and washed with deionized water. The above process was repeated 4 times to obtain a filter cake, which was dried in an oven at 100°C for 2 h to obtain NH4 + The molecular sieve was calcined at 520℃ for 3h to obtain the hydrogen type molecular sieve, which was recorded as FL1. The programmed temperature ammonia desorption NH3-TPD curve showed that the desorption peak temperature of the sample was 345℃.

[0182] Example 2

[0183] An aluminum-rich MCM-22 molecular sieve, the preparation method is as follows:

[0184] The silicon aluminum powder SAJ01 and KOH prepared in Preparation Example 1 are dissolved in methanol, and cyclopropylamine is added, wherein the molar ratio of SAJ01 (in terms of silicon element), NaOH, cycloheximide and deionized water is 1:0.20:0.44:35; after stirring evenly, a milky white gelling solution is obtained; the gelling solution is then charged into a polytetrafluoroethylene-lined pressure steel autoclave, and after pre-crystallization at a temperature of 90°C for 6 hours, it is placed in a rotary oven at a temperature of 150°C and a rotation speed of 20rpm for further hydrothermal crystallization for 160 hours, and then cooled to room temperature with tap water. The obtained product is filtered, washed, dried in an oven at 100°C for 2 hours, and then roasted at 550°C for 3 hours, cooled, and the molecular sieve raw powder is obtained.

[0185] The molecular sieve raw powder was tested, wherein the XRD test results showed that the obtained sample was a pure phase MWW configuration, with a relative crystallinity of 83%. SEM and TEM photos showed that the sample exhibited good microporous crystallinity. 27 The Al MASNMR results show that 84wt% of the aluminum species are in a four-coordinated state. The Si / Al ratio of this sample is 6.7, and the specific surface area S BET 506m 2 / g, micropore volume V micro 0.21m 3 / g.

[0186] The molecular sieve powder and 1 mol / L ammonium chloride aqueous solution were mixed evenly at a solid (mass, g) to liquid (volume, mL) ratio of 1:6, and heated in a water bath to 65°C for 1 h for ion exchange; then filtered and washed with deionized water. The above process was repeated 4 times to obtain a filter cake, which was dried in an oven at 100°C for 2 h to obtain NH4 + The molecular sieve was calcined at 520℃ for 3h to obtain the hydrogen type molecular sieve, which was recorded as FL2. The temperature-programmed ammonia desorption NH3-TPD curve showed that the desorption peak temperature of the sample was 330℃.

[0187] Example 3

[0188] An aluminum-rich MCM-22 molecular sieve, the preparation method is as follows:

[0189] The silicon aluminum powder SAJ01 and KOH prepared in Preparation Example 1 are dissolved in methanol, and cycloheximide and cyclooctylamine (the molar ratio of HMI to cyclooctylamine is 3.5:1) are added, wherein the molar ratio of SAJ01 (in terms of silicon element), NaOH, (cycloheximide and cyclooctylamine) to deionized water is 1:0.12:0.55:18; after stirring evenly, a milky white gelling solution is obtained; the gelling solution is then charged into a polytetrafluoroethylene-lined pressure steel autoclave, and after pre-crystallization at a temperature of 90°C for 6 hours, it is placed in a rotary oven at a temperature of 150°C and a rotation speed of 20 rpm for further hydrothermal crystallization for 160 hours, and then cooled to room temperature with tap water. The obtained product is filtered, washed, dried in an oven at 100°C for 2 hours, and then roasted at 550°C for 3 hours, and cooled to obtain molecular sieve raw powder.

[0190] The prepared molecular sieve raw powder was tested, wherein the XRD test results showed that the synthesized sample was a pure phase MWW configuration, with a relative crystallinity of 90%. SEM and TEM photos showed that the sample exhibited good microporous crystallinity. 27 The Al MASNMR results show that 91wt% of the aluminum species are in a four-coordinated state. The Si / Al ratio of this sample is 7.2, and the specific surface area S BET 487m 2 / g, micropore volume V micro 0.18m 3 / g.

[0191] The molecular sieve powder and 1 mol / L ammonium chloride aqueous solution were mixed evenly at a solid (mass, g) to liquid (volume, mL) ratio of 1:6, and heated in a water bath to 65°C for 1 h for ion exchange; then filtered and washed with deionized water. The above process was repeated 4 times to obtain a filter cake, which was dried in an oven at 100°C for 2 h to obtain NH4 + The molecular sieve was calcined at 520℃ for 3h to obtain the hydrogen type molecular sieve, which was recorded as FL3. The programmed temperature ammonia desorption NH3-TPD curve showed that the desorption peak temperature of the sample was 348℃.

[0192] Example 4

[0193] An aluminum-rich MCM-22 molecular sieve, the preparation method of which is the same as that of Example 1, except that the silicon aluminum powder SAJ01 is replaced by an equimolar amount (in terms of Si molar amount) of silicon aluminum powder SAJ02.

[0194] The prepared molecular sieve raw powder was tested, wherein the XRD test results showed that the synthesized sample was a pure phase MWW configuration, with a relative crystallinity of 88%. SEM and TEM photos showed that the sample exhibited good microporous crystallinity. 27 The Al MASNMR results show that 87wt% of the aluminum species are in a four-coordinated state. The Si / Al ratio of this sample is 4.5, and the specific surface area S BET 476m 2 / g, micropore volume V micro 0.20m 3 / g.

[0195] The molecular sieve powder and 1 mol / L ammonium chloride aqueous solution were mixed evenly at a solid (mass, g) to liquid (volume, mL) ratio of 1:6, and heated in a water bath to 65°C for 1 h for ion exchange; then filtered and washed with deionized water. The above process was repeated 4 times to obtain a filter cake, which was dried in an oven at 100°C for 2 h to obtain NH4 + The molecular sieve was calcined at 520℃ for 3h to obtain the hydrogen type molecular sieve, which was recorded as FL4. The programmed temperature ammonia desorption NH3-TPD curve showed that the desorption peak temperature of the sample was 327℃.

[0196] Comparative Example 1

[0197] A molecular sieve, the preparation method of which is the same as that of Example 1, except that the silicon aluminum powder SAJ01 is replaced by an equimolar amount (in terms of Si molar amount) of the comparison sample DBJ01.

[0198] The XRD test results of the product synthesized with DBJ01 as raw material showed a non-MWW configuration, with a large amount of amorphous matter and a small amount of GIS-configured eight-membered ring small-pore zeolite impurities. 27The Al MAS NMR results show that 34wt% of the aluminum species is in a four-coordinated state. The Si / Al ratio of this sample is 6.7, and the specific surface area S BET 306m 2 / g, micropore volume V micro 0.03m 3 / g.

[0199] The molecular sieve powder and 1 mol / L ammonium chloride aqueous solution were mixed evenly at a solid (mass, g) to liquid (volume, mL) ratio of 1:6, and heated in a water bath to 65°C for 1 h for ion exchange; then filtered and washed with deionized water. The above process was repeated 4 times to obtain a filter cake, which was dried in an oven at 100°C for 2 h to obtain NH4 + The molecular sieve was calcined at 520℃ for 3h to obtain the hydrogen type molecular sieve, which was recorded as DFL1. The programmed temperature ammonia desorption NH3-TPD curve showed that the desorption peak temperature of the sample was 336℃.

[0200] Comparative Example 2

[0201] A molecular sieve, the preparation method of which is the same as that of Example 1, except that the silicon aluminum powder SAJ01 is replaced by an equimolar amount (in terms of Si molar amount) of the comparison sample DBJ02.

[0202] The product synthesized from DBJ02 as raw material, XRD test results show that it is a mixture of MWW configuration and ANA configuration eight-membered ring small-pore zeolite impurities. 27 The Al MAS NMR results show that 79wt% of the aluminum species are in a four-coordinated state. The Si / Al ratio of this sample is 7.8, and the specific surface area S BET 345m 2 / g, micropore volume V micro 0.08m 3 / g.

[0203] The molecular sieve powder and 1 mol / L ammonium chloride aqueous solution were mixed evenly at a solid (mass, g) to liquid (volume, mL) ratio of 1:6, and heated in a water bath to 65°C for 1 h for ion exchange; then filtered and washed with deionized water. The above process was repeated 4 times to obtain a filter cake, which was dried in an oven at 100°C for 2 h to obtain NH4 + The molecular sieve was calcined at 520℃ for 3h to obtain the hydrogen type molecular sieve, which was recorded as DFL2. The programmed temperature ammonia desorption NH3-TPD curve showed that the desorption peak temperature of the sample was 386℃.

[0204] Comparative Example 3

[0205] A molecular sieve, the preparation method of which is the same as that of Example 1, except that the silicon aluminum powder SAJ01 is replaced by an equimolar amount (in terms of Si molar amount) of the comparative sample DBJ03.

[0206] The product synthesized from DBJ03 as raw material, XRD test results show that it is not MWW configuration, but a mixture of MFI configuration and GIS configuration of eight-membered ring small-pore zeolite impurities. 27 The Al MAS NMR results show that 82wt% of the aluminum species are in a four-coordinated state. The Si / Al ratio of this sample is 10.1, and the specific surface area S BET 297m 2 / g, micropore volume V micro 0.09m 3 / g.

[0207] The molecular sieve powder and 1 mol / L ammonium chloride aqueous solution were mixed evenly at a solid (mass, g) to liquid (volume, mL) ratio of 1:6, and heated in a water bath to 65°C for 1 h for ion exchange; then filtered and washed with deionized water. The above process was repeated 4 times to obtain a filter cake, which was dried in an oven at 100°C for 2 h to obtain NH4 + The molecular sieve was calcined at 520℃ for 3h to obtain the hydrogen type molecular sieve, which was recorded as DFL3. The temperature-programmed ammonia desorption NH3-TPD curve showed that the desorption peak temperature of the sample was 463℃.

[0208] Comparative Example 4

[0209] A molecular sieve, the preparation method of which is the same as that of Example 1, except that the silicon aluminum powder SAJ01 is replaced by an equimolar amount (in terms of Si molar amount) of the comparison sample DBJ04.

[0210] The product synthesized from DBJ04 as raw material, XRD test results show that it is not MWW configuration, but a mixture of FER configuration (ZSM-35) and GIS configuration octahedral small-pore zeolite impurities. 27 The Al MAS NMR results show that 77wt% of the aluminum species are in a tetracoordinated state. The Si / Al ratio of this sample is 11.6, and the specific surface area S BET 303m 2 / g, micropore volume V micro 0.07m 3 / g.

[0211] The molecular sieve powder and 1 mol / L ammonium chloride aqueous solution were mixed evenly at a solid (mass, g) to liquid (volume, mL) ratio of 1:6, and heated in a water bath to 65°C for 1 h for ion exchange; then filtered and washed with deionized water. The above process was repeated 4 times to obtain a filter cake, which was dried in an oven at 100°C for 2 h to obtain NH4 +The molecular sieve was calcined at 520℃ for 3h to obtain the hydrogen type molecular sieve, which was recorded as DFL4. The temperature-programmed ammonia desorption NH3-TPD curve showed that the desorption peak temperature of the sample was 398℃.

[0212] Comparative Example 5

[0213] A molecular sieve, the preparation method of which is the same as that of Example 1, except that cycloheximide and piperidine are replaced by equimolar amounts of imidazole.

[0214] The prepared molecular sieve raw powder was tested, and the XRD test results showed that the synthesized sample was a non-MWW configuration and a ZSM-35 product. The Si / Al ratio of the sample was 7.9, and the specific surface area S BET 386m 2 / g, micropore volume V micro 0.11m 3 / g.

[0215] The molecular sieve raw powder was ion exchanged and calcined, and the obtained molecular sieve was recorded as DFL5. The programmed temperature ammonia desorption NH3-TPD curve showed that the desorption peak temperature of the sample was 466℃.

[0216] Catalytic performance evaluation

[0217] The molecular sieves prepared in the examples and comparative examples were made into catalysts, and their catalytic performance was tested.

[0218] The molecular sieves prepared in each embodiment and comparative example were shaped into φ1mm×1mm particles; 800g was weighed, mixed evenly with 8g of an active component solution with a mass concentration of 5%, and then allowed to stand and impregnate for 12h at room temperature; the impregnated MCM-22 molecular sieve was then transferred to an oven and dried at a temperature of 110°C for 3h; the MCM-22 molecular sieve was then calcined at a temperature of 500°C for 3h in an air atmosphere to obtain a catalyst.

[0219] Take 5g of each of the above catalysts and load them into a stainless steel fixed bed tubular reactor, and reduce them with pure hydrogen. The reduction conditions are as follows: hydrogen flow rate 80mL / min, heating to 180℃ at 2℃ / min and keeping constant temperature for 2h, then heating to 375℃ at 2.5℃ / min and keeping constant temperature for 2h. Add raw material trimethylbenzene for selective dealkylation reaction, and the product is analyzed by HP6890 gas chromatography. Reaction conditions: reaction temperature 375℃, reaction pressure 0.6MPa, raw material weight space velocity 3.35h -1 , hydrogen to oil molar ratio 3. The statistics of the online reaction results for 100 h are shown in Table 7.

[0220] Activity (conversion rate C) and BTX selectivity (yield of high-quality low-carbon aromatics) are used as catalyst performance evaluation indicators.

[0221]

[0222] (TMB stands for trimethylbenzene, including 1,2,4-trimethylbenzene, 1,3,5-mesitylene and mixtures)

[0223] S BTX =(BTX in product / Σproduct)×100%

[0224] (B stands for benzene, T stands for toluene, and X stands for xylene)

[0225] Table 7

[0226] catalyst Molecular sieve Active ingredients <![CDATA[C TMB ]]> <![CDATA[S BTX <!-- 18 -->]]> A1 FL1 2%Nd 42％ 97％ A2 FL2 2%Nd 50％ 92％ A3 FL3 3%Nd 52％ 92.5％ A4 FL4 1.5%Nd 47％ 94％ A5 FL1 3%Nd 59％ 93％ A6 FL1 2.7%Nd 45％ 91％ A7 FL2 3% Ce 50％ 89％ D1 DFL1 2%Nd 2％ 20％ D2 DFL2 2%Nd 10％ 61％ D3 DFL3 2%Nd 8％ 73％ D4 DFL4 2%Nd 16％ 40％ D5 DFL5 2%Nd 11％ 90％

[0227] It should be noted that the embodiments described above are only used to explain the present invention and do not constitute any limitation to the present invention. The present invention has been described with reference to typical embodiments, but it should be understood that the words used therein are descriptive and explanatory words, rather than restrictive words. The present invention may be modified as specified within the scope of the claims of the present invention, and the present invention may be revised without departing from the scope and spirit of the present invention. Although the present invention described therein relates to specific methods, materials and embodiments, it does not mean that the present invention is limited to the specific examples disclosed therein, on the contrary, the present invention can be extended to all other methods and applications with the same functions.

Claims

1. A MCM-22 molecular sieve, characterized in that: The molar ratio of silicon to aluminum atoms in the MCM-22 molecular sieve is less than 10, and the relative crystallinity is greater than 80%.

2. The MCM-22 molecular sieve according to claim 1, characterized in that The molar ratio of silicon to aluminum atoms in the MCM-22 molecular sieve is less than 7.5; And / or, the acid strength of the MCM-22 molecular sieve is shown as a desorption peak temperature of programmed temperature ammonia desorption of 200 to 350°C; And / or, in the MCM-22 molecular sieve, the content of framework aluminum accounts for more than 60wt% of the total aluminum; And / or, the specific surface area S of the MCM-22 molecular sieve BET ≥400m 2 / g, micropore volume V micro >0.15cm 3 / g.

3. A method for preparing MCM-22 molecular sieve, characterized in that: include: S1. dissolving silicon aluminum powder, an alkali source and a template R in a solvent to form a colloid; the silicon aluminum atom molar ratio of the silicon aluminum powder is not less than 1, preferably 2 to 500; the surface hydroxyl concentration of the silicon aluminum powder is not less than 20 μmol / g, preferably not less than 30 μmol / g; S2. crystallizing the colloid obtained in step S1 to obtain the MCM-22 molecular sieve; Optionally, the method further comprises S3. calcining the MCM-22 molecular sieve once, then performing ion exchange, and then performing a second calcination.

4. The preparation method according to claim 3, characterized in that: The silicon aluminum powder is measured by solid nuclear magnetic resonance aluminum spectrum 27 In Al MAS NMR detection, the signal peak area of ​​hexacoordinated non-framework aluminum accounts for ≤50% of the total area of ​​all signal peaks, preferably ≤20%; And / or, the silicon aluminum powder is measured by solid nuclear magnetic resonance silicon spectroscopy 29 Si MAS NMR detection, the presence of Q 3 and Q 4 The characteristic signal of coordination, and Q 3 Coordination and Q 4 The ratio of the peak area of ​​the coordinated characteristic signal peak to the total area of ​​all signal peaks is ≥30%, preferably ≥60%; And / or, the silicon aluminum powder is detected by ultraviolet Raman spectroscopy at a vibration frequency of 240cm -1 There is a characteristic peak nearby; at the vibration frequency 335cm -1 、400cm -1 or 480cm -1 There is at least one characteristic peak near the vibration frequency of 335cm -1 、400cm -1 or 480cm -1 There is at least one characteristic peak with a peak intensity greater than the vibration frequency 240cm -1 The peak intensity of the nearby characteristic peaks; And / or, the specific surface area of ​​the silicon aluminum powder is 500 to 1200 m 2 / g; And / or, the pore volume of the silicon aluminum powder is 0.05 to 5 cm 3 / g.

5. The preparation method according to claim 3 or 4, characterized in that: The preparation method of the silicon aluminum powder comprises the following steps: (1) providing a mixed solution I containing a treatment reagent I and a solvent I; the treatment reagent I comprises a halogen-containing compound, preferably at least one selected from silicon tetrafluoride, silicon tetrachloride, ammonium fluoride, ammonium chloride, ammonium bromide, ammonium iodide, sodium fluoride, sodium chloride, sodium bromide, sodium iodide, hydrofluoric acid, hydrochloric acid and hydrobromic acid; Providing a mixed solution II containing a treatment reagent II and a solvent II; the treatment reagent II includes an acidic reagent, preferably at least one selected from ammonium nitrate, nitric acid, ammonium fluoride, ammonium chloride, hydrochloric acid, ammonium bromide, perbromic acid, carbonic acid, acetic acid, phosphoric acid, oxalic acid, formic acid, acetic acid, citric acid, ammonium iodide, iodine-containing acid, hydrofluoric acid and hydrobromic acid; (2) performing a first mixing treatment on the silicon-containing raw material and the mixed solution I to obtain a mixed solution III; Performing a second mixing process on the aluminum-containing raw material and the mixed solution II to obtain a mixed solution IV; (3) After mixing the mixed solution III and the mixed solution IV, the mixed solution is sequentially subjected to a standing treatment, a de-impurity treatment and a calcination treatment to obtain the silicon-aluminum powder.

6. The preparation method according to any one of claims 3 to 5, characterized in that: The solvent I and the solvent II are the same or different, and are independently selected from at least one of water, alcohols and ionic liquids; preferably selected from at least one of deionized water, methanol, ethanol, isopropanol, n-butanol, ethylene glycol, 1-butyl-3-methylimidazolium tetrafluoroborate and 1-butyl-3-methylimidazolium hexafluorophosphate; And / or, the silicon-containing raw material is selected from at least one of silicate, isobutylene triethoxysilane, tetramethylsilane, silicon tetrachloride, methyltrimethoxysilane, trichlorosilane, hexamethyldisilazane and hexamethyldisilchloroethane; And / or, the aluminum-containing raw material is selected from at least one of aluminum sulfate, aluminum chloride, aluminum nitrate, aluminum hydrogen phosphate, aluminum sol, pseudo-boehmite, aluminum oxide powder prepared by alcohol aluminum process, boehmite, α-alumina, β-alumina, γ-alumina and θ-alumina; and / or, the molar ratio of the treatment reagent I to SiO2 in the silicon-containing raw material is 0.0001 to 2:1; and / or, the molar ratio of the solvent I to SiO2 in the silicon-containing raw material is 0.5 to 100:1; and / or, the mass ratio of the treatment reagent II to Al2O3 in the aluminum-containing raw material is 0.0001 to 2:1, preferably 0.001 to 0.25:1; And / or, in the aluminum-containing mixed solution II, the mass fraction of Al2O3 is 0.1% to 60%, preferably 1% to 31%; And / or, in step (3), the conditions for the static treatment include: a temperature of -30 to 50°C; And / or, in step (3), the temperature of the de-doping treatment is 20 to 100°C; And / or, in the step (3), the conditions for the calcination treatment include: a temperature of 200-1200°C; preferably, within the temperature range of 250-1100°C, at least two calcination temperatures are selected from low to high in an air atmosphere for calcination; preferably, the calcination treatment is carried out at a temperature of 250-350°C, a temperature of 350-500°C, and a temperature of 500-1100°C, respectively.

7. The preparation method according to any one of claims 3 to 6, characterized in that: The alkali source includes alkali metal hydroxide and / or ammonia water; preferably, the alkali metal includes at least one of Li, Na, K, Ru, and Cs; And / or, the template R includes at least one of cycloheximide (HMI), piperidine, unequal tetraalkylammonium, N,N,N-trimethyl-1-adamantylammonium hydroxide, N,N,N-trimethyl-1-adamantylammonium bromide, pyridine, cyclopropylamine, cyclobutylamine, cyclooctylamine, and cyclohexylmethylamine; And / or, the solvent includes at least one of water, alcohol solvents, and imidazole-type ionic liquids; preferably, the solvent includes at least one of deionized water, methanol, ethanol, isopropanol, ethylene glycol, glycerol, acetone, and n-butanol; And / or, the molar ratio of the alkali source to the silicon element in the silicon-aluminum powder is: OH - / Si=0.1~0.25; And / or, the molar ratio of the solvent to the silicon element in the silicon-aluminum powder is: I / Si=5-50; And / or, the molar ratio of the template R to the silicon element in the silicon-aluminum powder is: R / Si=0.01-0.

95.

8. The preparation method according to any one of claims 3 to 7, characterized in that: The ion exchange comprises ammonium exchange; And / or, the number of ion exchanges is 1 to 20 times; And / or, after the ion exchange, filtering, washing and drying are first performed, and then secondary calcination is performed; preferably, the drying temperature is 30 to 200° C.; And / or, the crystallization stirring speed is 0 to 6000 rpm, the crystallization temperature is 80 to 200° C., and the crystallization time is 2 to 2000 hours; And / or, after the crystallization, the method further comprises filtering, washing and drying steps; preferably, the drying temperature is 30 to 200° C.; And / or, the primary calcination temperature is 200-980° C., and the primary calcination time is 0.1-250 h; And / or, the temperature of the secondary calcination is 400-650° C., and the time of the secondary calcination is 1-10 hours.

9. Use of the MCM-22 molecular sieve according to claim 1 or 2 or the MCM-22 molecular sieve prepared by the preparation method according to any one of claims 3 to 8 in aromatic hydrocarbon conversion.

10. An aromatic hydrocarbon conversion catalyst, characterized in that: The catalyst comprises the MCM-22 molecular sieve described in claim 1 or 2 or the MCM-22 molecular sieve prepared by the preparation method described in any one of claims 3 to 8.

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