Preparation method of p-xylene

Abstract

The present invention relates to catalysis field and is specifically related to a kind of preparation method of p-Xylene, the method including:Using 2,5-dimethylfurans and / or 2,5-hexanedione as raw material, the catalyst contains SCM-36 molecular sieves, and raw material and ethylene contact reaction prepare p-Xylene in the presence of alternatively organic solvent.Using SCM-36 molecular sieves as catalyst, under mild reaction conditions, 2,5-dimethylfurans and / or 2,5-hexanedione can be efficiently converted into p-Xylene, and conversion rate and product p-Xylene selectivity are very high.Meanwhile, in products obtained therefrom, key impurities (such as polyalkyl ethylbenzene, 2,5-hexanedione and 2-cyclopentenone) content is extremely low, greatly reducing separation energy consumption.In addition, the present invention has very high stability by using SCM-36 molecular sieves as catalyst, and is recycled four times without seeing catalyst performance significantly changed.

Description

Technical Field

[0001] The present invention relates to the field of catalysis, and in particular to a method for preparing p-xylene. Background Art

[0002] DMF acts as a dien and ethylene as a dienophile. They first undergo a Diels-Alder annulation reaction to form oxanorbornene, which then undergoes a dehydration reaction to form pX and water. Major side reactions include the hydrolysis of DMF to 2,5-hexanedione, the alkylation of pX with ethylene to form polyalkylbenzenes, and the polymerization of DMF and 2,5-hexanedione. The Dauenhauer group (ACS Catal. 2012, 2, 935-939) investigated the effects of different molecular sieves on the reaction performance. The results showed that HY molecular sieves performed best when used as a catalyst. At 300°C, the pX selectivity reached a maximum of only 75%, and a large amount of alkylbenzenes was produced, increasing the cost of product purification and separation, making it difficult to meet the requirements of large-scale production. The Fan group (ChemCatChem, 2017, 9, 398-402) used phosphorus-modified Beta molecular sieve to catalyze the reaction of DMF and ethylene at 250°C for 24 hours. The DMF conversion was complete and the product yield was as high as 97%. However, the catalytic stability was poor, which may be due to the loss of phosphorus. Subsequently, Feng et al. (Catal. Sci. Technol., 2017, 7, 5540-5549; CN 109569677A) designed and prepared a catalytic ... The bifunctional supported WO3 / SBA-15 molecular sieve catalyst of acid and Lewis acid can achieve the preparation of pX from DMF with high selectivity. However, the supported catalyst has disadvantages such as easy loss of active components and poor cyclic stability, which makes it difficult to achieve the needs of continuous production.

[0003] In summary, the existing technologies mainly have problems such as low product selectivity or poor catalyst cycle stability, which bring great problems to practical industrial applications. Summary of the Invention

[0004] The present invention addresses the problems of low product selectivity and poor catalyst cyclic stability in the prior art. The invention provides a method for preparing para-xylene. This method features efficient conversion of 2,5-dimethylfuran and / or 2,5-hexanedione under mild reaction conditions, high para-xylene selectivity, and outstanding catalyst cyclic stability.

[0005] In order to achieve the above-mentioned object, the present invention provides a method for preparing p-xylene, which comprises: using 2,5-dimethylfuran and / or 2,5-hexanedione as raw materials, the catalyst containing SCM-36 molecular sieve, and the raw materials are contacted with ethylene in the presence of an optional organic solvent to produce p-xylene.

[0006] The present invention provides a method for preparing p-xylene. By using SCM-36 molecular sieve as a catalyst, 2,5-dimethylfuran and / or 2,5-hexanedione can be efficiently converted into p-xylene under mild reaction conditions, with very high conversion rate and product p-xylene selectivity. At the same time, the content of key impurities (such as polyalkyl ethylbenzene, 2,5-hexanedione and 2-cyclopentenone) in the obtained product is extremely low, greatly reducing separation energy consumption. In addition, by using SCM-36 molecular sieve as a catalyst, the present invention has high stability, and no significant change in catalyst performance was observed after four cycles of use. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1 This is a scanning electron microscope (SEM) image of the molecular sieve obtained in Example 1 of the present invention;

[0008] Figure 2 is the XRD pattern of the molecular sieve obtained in Example 1 of the present invention;

[0009] Figure 3 This is the NH3-TPD diagram of the molecular sieve obtained in Example 1 of the present invention;

[0010] Figure 4 This is the Py-FTIR graph of the molecular sieve obtained in Example 1 of the present invention;

[0011] Figure 5 The conversion rate of 2,5-dimethylfuran and the selectivity of p-xylene under the recycling conditions of SCM-36 molecular sieve in Example 15 of the present invention are as follows;

[0012] Figure 6 NH3-TPD diagram of the molecular sieve obtained in Example 16;

[0013] Figure 7 This is the Py-FTIR graph of the molecular sieve obtained in Example 16. DETAILED DESCRIPTION

[0014] The endpoints of the ranges and any values ​​disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoints of each range, the endpoints of each range and individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered to be specifically disclosed herein.

[0015] The present invention provides a method for preparing p-xylene, which comprises: using 2,5-dimethylfuran and / or 2,5-hexanedione as raw materials, the catalyst containing SCM-36 molecular sieve, and contacting the raw materials with ethylene in the presence of an optional organic solvent to produce p-xylene. Using SCM-36 molecular sieve as a catalyst, under mild reaction conditions, 2,5-dimethylfuran and / or 2,5-hexanedione can be efficiently converted into p-xylene, and the conversion rate and product p-xylene selectivity are both very high. At the same time, the content of key impurities (such as polyalkyl ethylbenzene, 2,5-hexanedione and 2-cyclopentenone) in the obtained product is extremely low, greatly reducing separation energy consumption. In addition, the present invention has high stability by using SCM-36 molecular sieve as a catalyst, and no significant change in catalyst performance is observed after four cycles.

[0016] According to a preferred embodiment of the present invention, the SCM-36 molecular sieve has an illustrative chemical composition of "mSiO2·nAl2O3," where m / n is ≥ 5, preferably m / n = 15-40. This molecular sieve is beneficial for improving substrate conversion and product para-xylene selectivity, reducing the content of key impurities in the product, and improving the stability of the SCM-36 molecular sieve.

[0017] According to a preferred embodiment of the present invention, the total acid content of the SCM-36 molecular sieve is 400-1200 μmol·g -1 , preferably 500-1000 μmol·g -1 , wherein the weak acid content is ≥50%, preferably 55%-90%. The aforementioned SCM-36 molecular sieve has high stability and is beneficial for improving substrate conversion and product para-xylene selectivity, and reducing the content of key impurities in the product.

[0018] According to a preferred embodiment of the present invention, the Lewis acid / Bronst acid ratio of the SCM-36 molecular sieve is 0.1-3.8, preferably 0.5-3.5. The SCM-36 molecular sieve has high stability and is beneficial for improving substrate conversion and product para-xylene selectivity, while reducing the content of key impurities in the product.

[0019] According to a preferred embodiment of the present invention, the catalyst is SCM-36 molecular sieve, and the contact reaction is carried out in the presence of an organic solvent; the organic solvent has a wide range of optional types, and commonly used organic solvents can be used in the present invention. For the present invention, the organic solvent is preferably selected from one or more of n-hexane, n-heptane, γ-valerolactone, tetrahydrofuran, toluene and cyclohexane.

[0020] In the present invention, the catalyst dosage can be selected within a wide range and can be determined based on the reaction requirements. According to a preferred embodiment of the present invention, the mass ratio of the raw material to the catalyst is 0.6-30:1, preferably 1.0-10:1. This helps to improve substrate conversion and product para-xylene selectivity, while reducing the content of key impurities in the product.

[0021] In the present invention, the amount of organic solvent used can be selected within a wide range and can be determined based on the reaction requirements. According to a preferred embodiment of the present invention, the mass ratio of the organic solvent to the raw material is 8-60:1, preferably 10-30:1. This helps to improve substrate conversion and product para-xylene selectivity, while reducing the content of key impurities in the product.

[0022] In the present invention, the reaction conditions can be selected in a wide range and can be specifically determined according to the reaction requirements. According to the present invention, the reaction conditions preferably include: a reaction temperature of 160-340°C, preferably 220-270°C; and a reaction time that can be determined according to the temperature, for example, a reaction time of 6-64h, preferably 8-48h.

[0023] According to the present invention, the reaction conditions preferably include: a reaction pressure of 1-8 MPa, preferably 2-4 MPa.

[0024] According to a preferred embodiment of the present invention, the SCM-36 molecular sieve comprises an X-ray diffraction pattern as shown in the following table:

[0025]

[0026]

[0027] a: ±0.30°, b: varies with 2θ.

[0028] The SCM-36 molecular sieve having the aforementioned properties has high stability and is beneficial for improving substrate conversion and product paraxylene selectivity, and reducing the content of key impurities in the product.

[0029] In the present invention, in the XRD data of the molecular sieve, w, m, s, and vs represent the diffraction peak intensity, with w being weak, m being medium, s being strong, and vs being very strong, as is well known to those skilled in the art. Generally speaking, w is less than 20; m is 20-40; s is 40-70; and vs is greater than 70.

[0030] The data in the above table are expressed as SCM-36 molecular sieve at 2θ (°) (a) At 9.29, the interplanar spacing It is 9.485, the relative intensity (%) (I / I0)×100 is s (strong), and so on. Those skilled in the art are well aware of the representation method of the table, and the present invention will not explain them one by one here.

[0031] According to a preferred embodiment of the present invention, the SCM-36 molecular sieve comprises at least one diffraction peak in the X-ray diffraction pattern shown in the following table:

[0032]

[0033] a: ±0.30°, b: varies with 2θ.

[0034] The SCM-36 molecular sieve having the aforementioned properties has high stability and is beneficial for improving substrate conversion and product paraxylene selectivity, and reducing the content of key impurities in the product.

[0035] According to a preferred embodiment of the present invention, the specific surface area of ​​the SCM-36 molecular sieve is 320 to 640 m 2 / gram, preferably 360 to 480 meters 2 The SCM-36 molecular sieve with the aforementioned properties has high stability and is beneficial for improving substrate conversion and product para-xylene selectivity, while reducing the content of key impurities in the product.

[0036] According to a preferred embodiment of the present invention, the external specific surface area of ​​the SCM-36 molecular sieve is 50 to 300 m 2 / gram, preferably 100 to 220 meters 2 The SCM-36 molecular sieve with the aforementioned properties has high stability and is beneficial for improving substrate conversion and product para-xylene selectivity, while reducing the content of key impurities in the product.

[0037] According to a preferred embodiment of the present invention, the total pore volume of the SCM-36 molecular sieve is 0.3 to 1.2 cm 3 / gram, preferably 0.5 to 1 cm 3 The SCM-36 molecular sieve with the aforementioned properties has high stability and is beneficial for improving substrate conversion and product para-xylene selectivity, while reducing the content of key impurities in the product.

[0038] According to a preferred embodiment of the present invention, the micropore volume of the SCM-36 molecular sieve is 0.05 to 0.3 cm 3 / gram, preferably 0.09 to 0.25 cm 3 The SCM-36 molecular sieve with the aforementioned properties has high stability and is beneficial for improving substrate conversion and product para-xylene selectivity, while reducing the content of key impurities in the product.

[0039] According to a preferred embodiment of the present invention, the SCM-36 molecular sieve has a pore diameter of 0.3 to 0.7 nanometers, preferably 0.4 to 0.6 nanometers. The SCM-36 molecular sieve possessing the aforementioned properties is highly stable and beneficial for improving substrate conversion and product para-xylene selectivity, while reducing the content of key impurities in the product.

[0040] According to a preferred embodiment of the present invention, the specific surface area of ​​the SCM-36 molecular sieve is 320 to 640 m 2 / gram, preferably 360 to 480 meters 2 / g; external specific surface area is 50 to 300 m 2 / gram, preferably 100 to 220 meters 2 / g; the total pore volume of the molecular sieve is 0.30 to 1.20 cm 3 / gram, preferably 0.50 to 1.0 cm 3 / g; micropore volume is 0.10~0.30cm 3 / gram, preferably 0.15 to 0.25 cm 3 / gram; the pore diameter of the molecular sieve is 0.30 to 0.70 nanometers, preferably 0.40 to 0.60 nanometers.

[0041] According to a preferred embodiment of the present invention, the SCM-36 molecular sieve has a nano-platelet morphology, and the thickness of the crystal is less than 30 nanometers, preferably 10 to 20 nanometers.

[0042] In the present invention, the SCM-36 molecular sieve having the aforementioned properties has high stability, and is beneficial for improving substrate conversion and product para-xylene selectivity, and reducing the content of key impurities in the product.

[0043] In the present invention, the SCM-36 molecular sieve having the aforementioned properties can achieve the purpose of the present invention, and there is no special requirement for the preparation method. With respect to the present invention, the present invention provides a preparation method of the SCM-36 molecular sieve, which comprises the following steps:

[0044] A step of crystallizing a mixture comprising a silicon source, an aluminum source, a first organic template, a second organic template, an alkali source and water to obtain the molecular sieve; and optionally, further comprising a step of calcining the obtained molecular sieve;

[0045] The first organic template is selected from at least one of tetramethylammonium hydroxide, tetramethylammonium chloride, tetramethylammonium bromide and tetramethylammonium iodide;

[0046] The second organic template is selected from one or more of an alkylpyridine compound having a carbon number of C10-C16, a quaternary ammonium salt of an n-octyltrimethyl compound, and a quaternary ammonium base of an n-octyltrimethyl compound.

[0047] According to a preferred embodiment of the present invention, the molar ratio of the silicon source in terms of SiO2, the aluminum source in terms of Al2O3, the first organic template, the second organic template, the alkali source and water is 1:(0.01-0.20):(0.05-0.80):(0.05-0.80):(0.05-0.50):(8-80), preferably 1:(0.01-0.10):(0.08-0.65):(0.08-0.65):(0.08-0.45):(10-70), more preferably 1:(0.02-0.07):(0.10-0.50):(0.10-0.50):(0.10-0.40):(12-60). This is beneficial to improving substrate conversion and product para-xylene selectivity, and reducing the content of key impurities in the product.

[0048] According to a preferred embodiment of the present invention, the crystallization conditions of the mixture include: a crystallization temperature of 120 to 200° C., preferably 130 to 190° C., and more preferably 140 to 180° C. This is beneficial for improving substrate conversion and product para-xylene selectivity, and reducing the content of key impurities in the product.

[0049] According to a preferred embodiment of the present invention, the conditions for crystallizing the mixture include: a crystallization time of 1 to 15 days, preferably a crystallization time of 2 to 12 days; more preferably a crystallization time of 3 to 9 days.

[0050] According to a preferred embodiment of the present invention, the crystallization temperature of the mixture is 120-200°C, and the crystallization time is 1-15 days, preferably the crystallization temperature is 130-190°C, and the crystallization time is 2-12 days, more preferably the crystallization temperature is 140-180°C, and the crystallization time is 3-9 days.

[0051] According to a preferred embodiment of the present invention, the second organic template is selected from at least one of cetylpyridinium bromide, tetradecylpyridinium bromide, dodecylpyridinium bromide, cetylpyridinium chloride, tetradecylpyridinium chloride, cetylpyridinium hydroxide, n-octyltrimethylammonium chloride, n-octyltrimethylammonium bromide, and n-octyltrimethylammonium hydroxide; preferably, the second organic template is selected from at least one of cetylpyridinium bromide, tetradecylpyridinium bromide, dodecylpyridinium bromide, cetylpyridinium chloride, cetylpyridinium hydroxide, n-octyltrimethylammonium chloride, and n-octyltrimethylammonium bromide. This is beneficial for improving substrate conversion and product para-xylene selectivity, and reducing the content of key impurities in the product.

[0052] In the present invention, there is no special requirement for the types of silicon source, aluminum source and alkali source. According to a preferred embodiment of the present invention, the silicon source is selected from at least one of silicic acid, silica gel, silica sol, tetraethyl silicate and water glass.

[0053] According to a preferred embodiment of the present invention, the aluminum source is at least one selected from aluminum hydroxide, aluminum oxide, aluminate, aluminum salt and tetraalkoxyaluminum.

[0054] According to a preferred embodiment of the present invention, the alkali source is selected from at least one inorganic base having an alkali metal and / or an alkaline earth metal as a cation.

[0055] In the present invention, the reaction product p-xylene is qualitatively analyzed by gas chromatography-mass spectrometry (GC-MS), and the conversion of the substrate 2,5-methylfuran and / or 2,5-hexanedione and the yield of the reaction product pX are analyzed by gas chromatography (GC). The gas chromatograph is an Agilent 7890A, produced by Agilent Technologies, USA, and the chromatographic column is an HP-5 non-polar capillary column (30 m, 0.53 mm). The gas chromatograph is an Agilent 7890B, and the detector is a flame ionization detector (FID), and the chromatographic column is an SE-54 capillary column (30 m, 0.53 mm).

[0056] In the present invention, the XRD measurement method of the molecular sieve product is: the phase of the sample is analyzed by using a Japanese Rigaku Ultima IV X-ray powder diffractometer, and a CuKα ray source. Nickel filter, 2θ scanning range 2°-50°, operating voltage 35 kV, current 25 mA, scanning rate 10° / min.

[0057] In the present invention, the inductively coupled plasma atomic emission spectrometer (ICP) model is Varian 725-ES, and the analysis sample is dissolved in hydrofluoric acid to detect the content of the element.

[0058] In the present invention, the NH3 temperature-programmed desorption (NH3-TPD) experiment was carried out on a TPD / TPR Altamira AMI-3300 instrument, and the total acid content was calculated by fitting and peak separation of the obtained spectrum. The acid corresponding to the desorption temperature of 100-250°C was defined as a weak acid, and the proportion of the weak acid was calculated accordingly.

[0059] In the present invention, the scanning electron microscope (SEM) image was tested using Hitachi S-4800 of Japan Hitachi Co., Ltd., with a test voltage of 15KV.

[0060] In the present invention, the Py-FTIR graph is measured using a Thermo Nicolet 5700 FT-IR spectrometer.

[0061] In the present invention, the conversion formula of 2,5-dimethylfuran (or 2,5-hexanedione) is:

[0062] 2,5-dimethylfuran (and / or 2,5-hexanedione) conversion rate (%) = (molar amount of 2,5-dimethylfuran (and / or 2,5-hexanedione) participating in the reaction) / (molar amount of the reaction substrate 2,5-dimethylfuran (and / or 2,5-hexanedione)) × 100%.

[0063] In the present invention, the product p-xylene (pX) yield calculation formula is:

[0064] Yield % of product pX = (molar amount of pX produced by the reaction) / (molar amount of the reaction substrate 2,5-dimethylfuran (and / or 2,5-hexanedione)) × 100%.

[0065] In the present invention, the product paraxylene selectivity calculation formula is:

[0066] Selectivity of product pX % = (molar amount of pX produced by the reaction) / (molar amount of 2,5-dimethylfuran (and / or 2,5-hexanedione) reacted) × 100%.

[0067] In the context of this specification, for a molecular sieve, the substances other than water and metal ions that fill the pores during the synthesis of the molecular sieve (such as organic template molecules, etc.) are called "precursors" before they are removed.

[0068] In the context of this specification, the structure of the molecular sieve is determined by X-ray diffraction (XRD) patterns, which are measured by X-ray powder diffractometer using a Cu-Kα radiation source and a nickel filter. Prior to sample testing, the crystallization of the molecular sieve sample is observed using a scanning electron microscope (SEM) to confirm that the sample contains only one type of crystal, i.e., that the molecular sieve sample is pure phase. XRD testing is then performed on this basis to ensure that the diffraction peaks in the XRD pattern are free of interference peaks from other crystals.

[0069] In the context of this specification, specific surface area refers to the total surface area per unit mass of a sample, including both internal and external surface areas. Non-porous samples, such as Portland cement and some clay mineral powders, possess only external surface area. Porous and porous samples, such as asbestos fibers, diatomaceous earth, and molecular sieves, possess both external and internal surface areas. The surface area of ​​pores with a diameter less than 2 nanometers in porous and porous samples is considered the internal surface area. The surface area after deducting the internal surface area is called the external surface area. The external surface area per unit mass of a sample is referred to as the external specific surface area.

[0070] In the context of this specification, the so-called pore volume refers to the volume of pores per unit mass of porous material. The so-called total pore volume refers to the volume of all pores per unit mass of molecular sieve (generally only including pores with a pore diameter of less than 50 nanometers). The so-called micropore volume refers to the volume of all micropores per unit mass of molecular sieve (generally referring to pores with a pore diameter of less than 2 nanometers). The pore structure parameters of molecular sieves, such as total pore volume, micropore volume, total specific surface area and external specific surface area, are obtained by measuring the nitrogen physical adsorption and desorption isotherm of the molecular sieve using a physical adsorption instrument (such as the TriStar 3000 physical adsorption instrument from Mack Instruments, USA), and then calculating the obtained values ​​using the BET method and the t-plot method. The experimental conditions for nitrogen physical adsorption and desorption are as follows: the measurement temperature is -169°C, and the molecular sieve is vacuum pretreated at 300°C for 10 hours before measurement.

[0071] In the context of this specification, the so-called crystal thickness refers to observing the molecular sieve at a magnification of 100,000 times using a transmission electron microscope. A randomly selected observation field is then calculated as the average sum of the thicknesses of all plate-like crystals within that field. This operation is repeated 10 times. The average of the sum of the 10 average values ​​is taken as the crystal thickness.

[0072] The present invention is further illustrated by way of examples below, but the present invention is not limited to the scope of the examples. Experimental methods in the following examples where specific conditions are not specified were performed according to conventional methods and conditions, or selected according to the product specifications.

[0073] The reagents and raw materials used in the present invention are commercially available.

[0074] In the present invention, if the data in the table is inconsistent with the examples, the data in the examples shall prevail.

[0075] Example 1

[0076] 1) Preparation of SCM-36 molecular sieve

[0077] 24.73 g of deionized water, 6.89 g of a sodium hydroxide aqueous solution (containing 10 wt% of NaOH), 5.35 g of a first organic template tetramethylammonium hydroxide aqueous solution (containing 25 wt% of TMAOH), 3.05 g of a second organic template n-octyltrimethylammonium chloride, 0.987 g of sodium metaaluminate (containing 40.5 wt% of Al2O3 and 30.6 wt% of Na2O), and 14.72 g of silica sol (containing 40 wt% of SiO2) were uniformly mixed to prepare a mixture. The material ratio (molar ratio) of the reactants was:

[0078] Al2O3 / SiO2=0.04

[0079] Tetramethylammonium hydroxide (A) / SiO2=0.15

[0080] n-Octyltrimethylammonium chloride (B) / SiO2=0.15

[0081] NaOH / SiO2=0.30

[0082] H2O / SiO2=25;

[0083] After uniform mixing, the mixture was placed in a stainless steel reactor and crystallized at 170°C for 5 days. After crystallization, the mixture was filtered, washed, dried in an oven at 110°C for 12 hours, and calcined in air at 550°C for 6 hours to obtain a molecular sieve.

[0084] The SEM images of the samples are as follows Figure 1 As shown by Figure 1 It can be seen that the SCM-36 molecular sieve has a flake morphology. The XRD spectrum data of the sample are shown in Table 1 and Figure 2 As shown by Figure 2 It can be seen that SCM-36 molecular sieve has a high degree of crystallinity.

[0085] Table 1

[0086]

[0087] The specific surface area of ​​the calcined product is 383 m 2 / g, with an external surface area of ​​174 m 2 / g, total pore volume 0.75 cm 3 / g, micropore volume is 0.12 cm 3 The sample has a micropore size distribution of 0.59 nm. The sample has a nanoplatelet morphology, with a crystal thickness of approximately 15 nm. Inductively coupled plasma atomic emission spectroscopy (ICP) analysis revealed a SiO2 / Al2O3 molar ratio of 25.6 for the calcined sample.

[0088] The ammonia temperature programmed desorption (NH3-TPD) spectrum of the sample is as follows: Figure 3 As shown, the total amount of acid obtained is 782 μmol·g- 1 , the weak acid content is 63%. Pyridine adsorption infrared spectrum is as follows Figure 4 As shown, the Lewis / Bronst acid ratio was determined analytically to be 2.2.

[0089] 2) Preparation of p-xylene

[0090] The reaction solvent was n-heptane, with a mass ratio of n-heptane to DMF of 20 and a mass ratio of DMF to catalyst of 1. The reaction temperature was 240°C, and the reaction time was 24 hours. 1.0 g of the SCM-36 molecular sieve prepared above, 1.0 g of DMF, and 20 g of n-heptane were added to a stirred autoclave, and 2.0 MPa of ethylene was introduced. The temperature was raised to a preset temperature using a programmed heating mantle, and magnetic stirring was employed followed by stirring. The reaction was continued at 240°C for 24 hours. Gas phase analysis of the reaction liquid revealed a DMF conversion of 86%, a pX selectivity of 94%, and a selectivity for the key impurity, polyalkylbenzene, of less than 1%.

[0091] Example 2

[0092] The same as Example 1, except that cetylpyridinium bromide is used as the second organic template, the material ratio (molar ratio) of the reactants is:

[0093] Al2O3 / SiO2=0.045

[0094] Tetramethylammonium hydroxide (A) / SiO2=0.15

[0095] Cetylpyridinium bromide (B) / SiO2=0.20

[0096] NaOH / SiO2=0.25

[0097] H2O / SiO2=30;

[0098] After uniform mixing, the mixture was placed in a stainless steel reactor and crystallized at 160°C for 6 days. After crystallization, the mixture was filtered, washed, dried in an oven at 90°C for 12 hours, and calcined in air at 550°C for 6 hours to obtain a molecular sieve.

[0099] The XRD spectrum data of the dried sample are shown in Table 2, and the SEM images of the sample are shown in Table 2. Figure 1 similar.

[0100] Table 2

[0101]

[0102]

[0103] The specific surface area of ​​the calcined product is 394 m 2 / g, with an external surface area of ​​171 m 2 / g, total pore volume 0.68 cm 3 / g, micropore volume is 0.12 cm 3The sample has a micropore size distribution of 0.59 nm. The sample has a nanoplatelet morphology, with a crystal thickness of approximately 12 nm. Inductively coupled plasma atomic emission spectroscopy (ICP) analysis revealed a SiO2 / Al2O3 molar ratio of 22.8 for the calcined sample.

[0104] The ammonia temperature programmed desorption (NH3-TPD) of the sample was similar to that of Figure 3 Similarly, the total amount of acid thus obtained was 827 μmol·g- 1 , weak acid content is 61%. Pyridine adsorption infrared spectrum and Figure 4 Similarly, the Lewis / Bronst acid ratio was determined analytically to be 2.5.

[0105] 2) Preparation of p-xylene

[0106] The reaction solvent was n-heptane, with a mass ratio of n-heptane to DMF of 20 and a mass ratio of DMF to catalyst of 1. The reaction temperature was 240°C, and the reaction time was 24 hours. 1.0 g of the SCM-36 molecular sieve prepared above, 1.0 g of DMF, and 20 g of n-heptane were added to a stirred autoclave, and 2.0 MPa of ethylene was introduced. The temperature was raised to a preset temperature using a programmed heating mantle, and magnetic stirring was employed followed by stirring. The reaction was continued at 240°C for 24 hours. Gas phase analysis of the reaction liquid revealed a DMF conversion of 90%, a pX selectivity of 94%, and a selectivity for the key impurity, polyalkylbenzene, of less than 1%.

[0107] Example 3

[0108] Same as Example 1, except that:

[0109] Al2O3 / SiO2=0.03

[0110] Tetramethylammonium iodide (A) / SiO2=0.20

[0111] n-Octyltrimethylammonium chloride (B) / SiO2=0.20

[0112] NaOH / SiO2=0.25

[0113] H2O / SiO2=35;

[0114] After uniform mixing, the mixture was placed in a stainless steel reactor and crystallized at 170°C for 5 days. After crystallization, the mixture was filtered, washed, dried in an oven at 100°C for 12 hours, and calcined in air at 500°C for 10 hours to obtain a molecular sieve.

[0115] The XRD spectrum data of the dried sample are shown in Table 3, and the SEM images of the sample are shown in Table 3. Figure 1 similar.

[0116] Table 3

[0117]

[0118]

[0119] The specific surface area of ​​the calcined product is 362 m 2 / g, with an external specific surface area of ​​149 m 2 / g, total pore volume 0.67 cm 3 / g, micropore volume is 0.10 cm 3 The sample's micropore diameters were 0.59 nm and 0.67 nm, respectively. The sample exhibited a nanoplatelet-like morphology, with a crystal thickness of approximately 12 nm. Inductively coupled plasma atomic emission spectroscopy (ICP) analysis revealed a SiO₂ / Al₂O₃ molar ratio of 34.5 for the calcined sample.

[0120] The ammonia temperature programmed desorption (NH3-TPD) of the sample was similar to that of Figure 3 Similarly, the total amount of acid obtained was 674 μmol·g- 1 , weak acid content is 68%. Pyridine adsorption infrared spectrum and Figure 4 Similarly, the Lewis / Bronst acid ratio was determined analytically to be 1.1.

[0121] 2) Preparation of p-xylene

[0122] The reaction solvent was n-heptane, with a mass ratio of n-heptane to DMF of 20 and a mass ratio of DMF to catalyst of 1. The reaction temperature was 240°C, and the reaction time was 24 hours. 1.0 g of the SCM-36 molecular sieve prepared above, 1.0 g of DMF, and 20 g of n-heptane were added to a stirred autoclave, and 2.0 MPa of ethylene was introduced. The temperature was raised to a preset temperature using a programmed heating mantle, and magnetic stirring was employed followed by stirring. The reaction was continued at 240°C for 24 hours. Gas phase analysis of the reaction liquid revealed a DMF conversion of 86%, a pX selectivity of 95%, and a selectivity for the key impurity, polyalkylbenzene, of less than 1%.

[0123] Example 4

[0124] 24.73 g of deionized water, 6.89 g of a sodium hydroxide aqueous solution (containing 10 wt% of NaOH), 5.35 g of a first organic template tetramethylammonium hydroxide aqueous solution (containing 25 wt% of TMAOH), 3.05 g of a second organic template n-octyltrimethylammonium chloride, 1.234 g of sodium metaaluminate (containing 40.5 wt% of Al2O3 and 30.6 wt% of Na2O), and 14.72 g of silica sol (containing 40 wt% of SiO2) were uniformly mixed to prepare a mixture. The material ratio (molar ratio) of the reactants was:

[0125] Al2O3 / SiO2=0.05

[0126] Tetramethylammonium hydroxide (A) / SiO2=0.15

[0127] n-Octyltrimethylammonium chloride (B) / SiO2=0.15

[0128] NaOH / SiO2=0.30

[0129] H2O / SiO2=25;

[0130] After uniform mixing, the mixture was placed in a stainless steel reactor and crystallized at 160°C for 6 days. After crystallization, the mixture was filtered, washed, dried in an oven at 110°C for 12 hours, and calcined in air at 550°C for 6 hours to obtain a molecular sieve.

[0131] The XRD spectrum data of the dried sample are shown in Table 4, and the SEM images of the sample are shown in Table 4. Figure 1 Similar.

[0132] Table 4

[0133]

[0134] The specific surface area of ​​the calcined product is 380 m 2 / g, with an external surface area of ​​170 m 2 / g, total pore volume 0.92 cm 3 / g, micropore volume is 0.10 cm 3 The sample has a micropore size distribution of 0.67 nm. The sample has a nanoplatelet morphology, with a crystal thickness of approximately 15 nm. Inductively coupled plasma atomic emission spectroscopy (ICP) analysis revealed a SiO2 / Al2O3 molar ratio of 21.6 for the calcined sample.

[0135] The ammonia temperature programmed desorption (NH3-TPD) of the sample was similar to that of Figure 3 Similarly, the total amount of acid thus obtained was 835 μmol·g- 1 , the weak acid content is 64%. Pyridine adsorption infrared spectrum and Figure 4 Similarly, the Lewis / Bronst acid ratio was determined analytically to be 2.8.

[0136] 2) Preparation of p-xylene

[0137] The reaction solvent was n-heptane, with a mass ratio of n-heptane to DMF of 20 and a mass ratio of DMF to catalyst of 1. The reaction temperature was 240°C, and the reaction time was 24 hours. 1.0 g of the SCM-36 molecular sieve prepared above, 1.0 g of DMF, and 20 g of n-heptane were added to a stirred autoclave, and 2.0 MPa of ethylene was introduced. The temperature was raised to a preset temperature using a programmed heating mantle, and magnetic stirring was employed followed by stirring. The reaction was continued at 240°C for 24 hours. Gas phase analysis of the reaction liquid revealed a DMF conversion of 92%, a pX selectivity of 95%, and a selectivity for the key impurity, polyalkylbenzene, of less than 1%.

[0138] Example 5

[0139] The present embodiment adopts normal heptane as reaction solvent, the mass ratio of normal heptane to 2,5-dimethylfuran (DMF) is 20, the mass ratio of DMF to catalyst is 1.5, the reaction temperature is 250 ℃, and the reaction time is 30h. 1.0g of the SCM-36 molecular sieve catalyst in the above-mentioned embodiment 1, 1.5g of DMF and 30g of normal heptane are added to a stirred autoclave, and 3.0MPa of ethylene is charged. The temperature is raised to a preset temperature using a programmed heating mantle, and magnetic stirring is then used to stir. The reaction is carried out at 250 ℃ for 30h. The reaction liquid gas phase analysis shows that the DMF conversion is 88%, the pX selectivity is 96%, and the key impurity polyalkylbenzene selectivity is less than 1%.

[0140] Example 6

[0141] In this example, n-heptane was used as the reaction solvent. The mass ratio of n-heptane to 2,5-hexanedione (HDO) was 20, the mass ratio of HDO to catalyst was 1, the reaction temperature was 230°C, and the reaction time was 20 hours. 1.0 g of the SCM-36 molecular sieve catalyst from Example 1 above, 1 g of HDO, and 20 g of n-heptane were added to a stirred autoclave and charged with 2.0 MPa of ethylene. The reaction was heated to the preset temperature using a programmed heating mantle and then stirred using magnetic stirring. The reaction was continued at 230°C for 20 hours. Gas phase analysis of the reaction liquid revealed an HDO conversion of 86%, a pX selectivity of 95%, and a selectivity for the key impurity, polyalkylbenzenes, of less than 1%.

[0142] Example 7

[0143] The present embodiment adopts normal hexane as reaction solvent, the mass ratio of normal hexane to 2,5-dimethylfuran (DMF) is 30, the mass ratio of DMF to catalyst is 2, the reaction temperature is 260 ℃, and the reaction time is 24h. 1.0g of the SCM-36 molecular sieve catalyst in the above-mentioned embodiment 1, 2.0g of DMF and 60g of normal hexane are added into a stirred autoclave, and 4.0MPa of ethylene is charged into it. The temperature is raised to the preset temperature by a programmed heating mantle, and magnetic stirring is then adopted to stir. The reaction is carried out at 260 ℃ for 24h. The DMF conversion rate calculated by gas phase analysis of the reaction liquid is 83%, the pX selectivity is 94%, and the selectivity of the key impurity polyalkylbenzene is less than 1%.

[0144] Example 8

[0145] The present embodiment adopts normal hexane as reaction solvent, normal hexane and 2,5-dimethylfuran (DMF) mass ratio is 20, DMF and catalyst mass ratio is 1.5, reaction temperature is 240 ℃, reaction time is 30h. 1.0g SCM-36 molecular sieve catalyst in above-mentioned embodiment 1, 1.5g DMF and 30g normal hexane are added into the autoclave with stirring, and are filled with 2.0MPa ethylene. Adopt programmed temperature heating mantle to rise to preset temperature, and adopt magnetic stirring and then stir. Under 240 ℃ condition, reaction is 30h, and the DMF conversion rate of reaction liquid gas phase analysis calculation is 88%, pX selectivity is 93%, and key impurity polyalkylbenzene selectivity is less than 1%.

[0146] Example 9

[0147] In this example, γ-valerolactone was used as the reaction solvent. The mass ratio of γ-valerolactone to 2,5-hexanedione (HDO) was 1:15, the mass ratio of HDO to catalyst was 2:1, the reaction temperature was 270°C, and the reaction time was 28 hours. 1.0 g of the SCM-36 molecular sieve catalyst from Example 1 above, 2 g of HDO, and 30 g of γ-valerolactone were added to a stirred autoclave and charged with 3.0 MPa of ethylene. The reaction was heated to the preset temperature using a programmed heating mantle and then stirred using magnetic stirring. The reaction was continued at 270°C for 28 hours. Gas phase analysis of the reaction liquid revealed an HDO conversion of 89%, a pX selectivity of 95%, and a selectivity for the key impurity, polyalkylbenzenes, of less than 1%.

[0148] Example 10

[0149] In this embodiment, γ-valerolactone is used as the reaction solvent. The mass ratio of γ-valerolactone to 2,5-dimethylfuran (DMF) is 30, the mass ratio of DMF to catalyst is 3, the reaction temperature is 270°C, and the reaction time is 32h. 1.0g of the SCM-36 molecular sieve catalyst, 3.0g of DMF, and 90g of γ-valerolactone in the above-mentioned embodiment 1 are added to a stirred autoclave and charged with 4.0MPa of ethylene. The temperature is raised to a preset temperature using a programmed heating mantle, and magnetic stirring is then used to stir. The reaction is carried out at 270°C for 32h. The DMF conversion rate calculated by gas phase analysis of the reaction liquid is 85%, the pX selectivity is 94%, and the selectivity of the key impurity polyalkylbenzene is less than 1%.

[0150] Example 11

[0151] In this example, toluene was used as the reaction solvent. The mass ratio of toluene to 2,5-hexanedione (HDO) was 2:2, the mass ratio of HDO to catalyst was 1, the reaction temperature was 250°C, and the reaction time was 18 hours. 1.0 g of the SCM-36 molecular sieve catalyst from Example 1 above, 1 g of HDO, and 22 g of toluene were added to a stirred autoclave, and 2.0 MPa of ethylene was introduced. The reaction was heated to the preset temperature using a programmed heating mantle, and then stirred using magnetic stirring. The reaction was continued at 250°C for 18 hours. Gas phase analysis of the reaction liquid revealed an HDO conversion of 93%, a pX selectivity of 95%, and a selectivity for the key impurity, polyalkylbenzenes, of less than 1%.

[0152] Example 12

[0153] In this example, toluene was used as the reaction solvent. The mass ratio of toluene to 2,5-hexanedione (HDO) was 25, the mass ratio of HDO to catalyst was 1.5, the reaction temperature was 260°C, and the reaction time was 24 hours. 1.0 g of the SCM-36 molecular sieve catalyst from Example 1 above, 1.5 g of HDO, and 37.5 g of toluene were added to a stirred autoclave and filled with 4.0 MPa of ethylene. The reaction was heated to the preset temperature using a programmed heating mantle and then stirred using magnetic stirring. The reaction was continued at 260°C for 24 hours. Gas phase analysis of the reaction liquid revealed an HDO conversion of 90%, a pX selectivity of 95%, and a selectivity for the key impurity, polyalkylbenzenes, of less than 1%.

[0154] Example 13

[0155] The present embodiment adopts cyclohexane as reaction solvent, cyclohexane and 2,5-dimethylfuran (DMF) mass ratio is 30, DMF and catalyst mass ratio is 2, reaction temperature is 250 ℃, reaction time is 40h. 1.0g SCM-36 molecular sieve catalyst, 2.0g DMF and 60g cyclohexane in above-mentioned embodiment 1 are added into the autoclave with stirring, and are filled with 4.0MPa ethylene. Adopt programmed temperature raising heating mantle to rise to preset temperature, and adopt magnetic stirring and then stir. React under 250 ℃ condition for 40h, the DMF conversion of reaction liquid is calculated by gas phase analysis and is 86%, pX selectivity is 96%, and key impurity polyalkylbenzene selectivity is less than 1%.

[0156] Example 14

[0157] In this example, cyclohexane was used as the reaction solvent. The mass ratio of cyclohexane to 2,5-hexanedione (HDO) was 20, the mass ratio of HDO to catalyst was 2, the reaction temperature was 255°C, and the reaction time was 38 hours. 1.0 g of the SCM-36 molecular sieve catalyst from Example 1 above, 2.0 g of HDO, and 40.0 g of cyclohexane were added to a stirred autoclave and charged with 4.0 MPa of ethylene. The reaction was heated to the preset temperature using a programmed heating mantle and then stirred using magnetic stirring. The reaction was continued at 255°C for 38 hours. Gas phase analysis of the reaction liquid revealed an HDO conversion of 87%, a pX selectivity of 95%, and a selectivity for the key impurity, polyalkylbenzenes, of less than 1%.

[0158] To more intuitively describe the reaction conditions and results of Examples 5-14 above, various parameters and results are listed in Table 5.

[0159] Table 5 Catalytic performance results of Examples 5-14

[0160]

[0161] Example 15

[0162] n-Heptane was used as the reaction solvent, the mass ratio of n-heptane to DMF was 20, the mass ratio of DMF to catalyst was 1, the reaction temperature was 240°C, and the reaction time was 24h. 1.0g of the SCM-36 molecular sieve prepared above, 1.0g of DMF and 20g of n-heptane were added to a high-pressure reactor with stirring, and filled with 2.0MPa of ethylene. The temperature was raised to the preset temperature using a programmed heating jacket, and magnetic stirring was used and then stirred. The reaction was carried out at 240°C for 24h, and the DMF conversion rate and pX selectivity were calculated by gas phase analysis of the reaction liquid. The used catalyst was washed and dried and then put into the next reaction. The reaction was repeated 4 times in total, and the results are as follows Figure 5The results show that after four reactions, the DMF conversion rate remained above 82%, the pX selectivity remained at 92%, and the selectivity of the key impurity polyalkylbenzene was less than 1%, indicating that the SCM-36 molecular sieve has good cyclic stability.

[0163] Example 16

[0164] Same as Example 1, except that:

[0165] Al2O3 / SiO2=0.017

[0166] Tetramethylammonium hydroxide (A) / SiO2=0.20

[0167] n-Octyltrimethylammonium chloride (B) / SiO2=0.25

[0168] NaOH / SiO2=0.20

[0169] H2O / SiO2=30;

[0170] After uniform mixing, the mixture was placed in a stainless steel reactor and crystallized at 155°C for 8 days. After crystallization, the mixture was filtered, washed, dried in an oven at 120°C for 6 hours, and calcined in air at 550°C for 8 hours to obtain a molecular sieve.

[0171] The XRD spectrum data of the dried sample are shown in Table 6, and the SEM images of the sample are shown in Table 6. Figure 1 similar.

[0172] Table 6

[0173]

[0174]

[0175] The specific surface area of ​​the calcined product is 372 m 2 / g, with an external specific surface area of ​​149 m 2 / g, total pore volume 0.74 cm 3 / g, micropore volume is 0.09 cm 3 The sample's micropore diameters were 0.60 nm and 0.67 nm, respectively. The sample exhibited a nanoplatelet-like morphology, with a crystal thickness of approximately 12 nm. Inductively coupled plasma atomic emission spectroscopy (ICP) analysis revealed a SiO₂ / Al₂O₃ molar ratio of 61.5 for the calcined sample.

[0176] The ammonia temperature programmed desorption (NH3-TPD) of the sample is as follows Figure 6 As shown, the total amount of acid obtained is 470 μmol·g- 1 , the weak acid content is 47%. Pyridine adsorption infrared spectrum is as follows Figure 7As shown, the Lewis / Bronst acid ratio was determined analytically to be 0.4.

[0177] 2) Preparation of p-xylene

[0178] The reaction solvent was n-heptane, with a mass ratio of n-heptane to DMF of 20 and a mass ratio of DMF to catalyst of 1. The reaction temperature was 240°C, and the reaction time was 24 hours. 1.0 g of the SCM-36 molecular sieve prepared above, 1.0 g of DMF, and 20 g of n-heptane were added to a stirred autoclave, and 2.0 MPa of ethylene was introduced. The temperature was raised to a preset temperature using a programmed heating mantle, and magnetic stirring was employed followed by stirring. The reaction was continued at 240°C for 24 hours. Gas phase analysis of the reaction liquid revealed a DMF conversion of 76%, a pX selectivity of 81%, and an 8% selectivity for the key impurity, polyalkylbenzene.

[0179] Comparative Example 1

[0180] AlPO-17 molecular sieve was prepared according to the literature (Microporous and Mesoporous Materials, 2018, 263, 11-20). Phosphoric acid, aluminum isopropoxide, cyclohexylamine, and deionized water were mixed uniformly to form a gel according to the ratio of 1P2O5:0.9Al2O3:1CHA (cyclohexylamine):50H2O. The gel was then hydrothermally crystallized at 190°C for 120 hours. After washing and drying, the AlPO-17 molecular sieve was calcined at 550°C in air for 5 hours. The total acid content of the sample was 262μmol·g -1 , of which the weak acid content is 93% and the Lewis acid / Bronst acid ratio is 4.2.

[0181] The reaction solvent was n-heptane, with a mass ratio of n-heptane to DMF of 20 and a mass ratio of DMF to catalyst of 1. The reaction temperature was 240°C, and the reaction time was 24 hours. 1 g of the catalyst from Comparative Example 1, 1.0 g of DMF, and 20 g of n-heptane were added to a stirred autoclave, which was then charged with 2.0 MPa of ethylene. The temperature was raised to the preset temperature using a programmed heating mantle, followed by magnetic stirring. The reaction was continued at 240°C for 24 hours. Gas phase analysis of the reaction liquid revealed a DMF conversion of 67% and a pX selectivity of 72%.

[0182] The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, various simple variations of the technical solution of the present invention may be made, including combining the various technical features in any other appropriate manner. These simple variations and combinations should also be regarded as disclosed in the present invention and fall within the scope of protection of the present invention.

Claims

1. A method for preparing p-xylene, characterized in that: The method comprises: using 2,5-dimethylfuran and / or 2,5-hexanedione as raw materials, a catalyst containing SCM-36 molecular sieve, and contacting the raw materials with ethylene in the presence of an optional organic solvent to produce p-xylene; The SCM-36 molecular sieve has a schematic chemical composition of "mSiO2•nAl2O3", where m / n≥5; The SCM-36 molecular sieve includes an X-ray diffraction pattern as shown in the following table: a: ±0.30°, b: varies with 2θ.

2. The method according to claim 1, wherein m / n=15-40; and / or The total acid content of the SCM-36 molecular sieve is 400-1200 μmol•g -1 , wherein the weak acid content is ≥50%; and / or The Lewis acid / Bronst acid ratio of the SCM-36 molecular sieve is 0.1-3.

8.

3. The method according to claim 2, wherein: The total acid content of the SCM-36 molecular sieve is 500-1000µmol•g -1 , wherein the weak acid content is 55%-90%; and / or The Lewis acid / Bronst acid ratio of the SCM-36 molecular sieve is 0.5-3.

5.

4. The method according to claim 1, wherein The catalyst is SCM-36 molecular sieve, and the contact reaction is carried out in the presence of an organic solvent; The organic solvent is selected from one or more of n-hexane, n-heptane, γ-valerolactone, tetrahydrofuran, toluene and cyclohexane; and / or The mass ratio of the raw material to the catalyst is 0.6-30:1; and / or The mass ratio of the organic solvent to the raw material is 8-60:

1.

5. The method according to claim 4, wherein The mass ratio of the raw material to the catalyst is 1.0-10:1; and / or The mass ratio of the organic solvent to the raw material is 10-30:

1.

6. The method according to claim 1, wherein The reaction conditions include: The reaction temperature is 160-340°C; and / or The reaction time is 6-64 hours; and / or The reaction pressure is 1-8MPa.

7. The method according to claim 6, wherein: The reaction conditions include: The reaction temperature is 220-270°C; and / or The reaction time is 18-40 hours; and / or The reaction pressure is 2-4 MPa.

8. The method according to claim 7, wherein: The reaction conditions include: The reaction time is 18-40h.

9. The method according to claim 1, wherein The SCM-36 molecular sieve comprises at least one diffraction peak in the X-ray diffraction pattern shown in the following table: a: ±0.30°, b: varies with 2θ.

10. The method according to claim 1 or 2, wherein: The specific surface area of ​​the SCM-36 molecular sieve is 320~640 m 2 / g; and / or The external specific surface area of ​​the SCM-36 molecular sieve is 50 to 300 m 2 / g; and / or The total pore volume of the SCM-36 molecular sieve is 0.3 to 1.2 cm 3 / g; and / or The micropore volume of the SCM-36 molecular sieve is 0.05~0.3 cm 3 / g; and / or The pore size of the SCM-36 molecular sieve is 0.3 to 0.7 nanometers; and / or The SCM-36 molecular sieve has a nano-sheet morphology, and the thickness of the crystal is less than 30 nanometers.

11. The method according to claim 1 or 2, wherein: The specific surface area of ​​the SCM-36 molecular sieve is 360~480 m 2 / g; and / or The external specific surface area of ​​the SCM-36 molecular sieve is 100~220 m 2 / g; and / or The total pore volume of the SCM-36 molecular sieve is 0.5 to 1 cm 3 / g; and / or The micropore volume of the SCM-36 molecular sieve is 0.09~0.25 cm 3 / g; and / or The pore size of the SCM-36 molecular sieve is 0.4 to 0.6 nanometers; and / or The thickness of the SCM-36 molecular sieve crystal is 10 to 20 nanometers.

12. The method according to claim 1 or 2, wherein: The preparation method of the SCM-36 molecular sieve comprises: A step of crystallizing a mixture comprising a silicon source, an aluminum source, a first organic template, a second organic template, an alkali source and water to obtain the molecular sieve; and optionally, further comprising a step of calcining the obtained molecular sieve; The first organic template is selected from at least one of tetramethylammonium hydroxide, tetramethylammonium chloride, tetramethylammonium bromide and tetramethylammonium iodide; The second organic template is selected from one or more of an alkylpyridine compound having a carbon number of C10-C16, a quaternary ammonium salt of an n-octyltrimethyl compound, and a quaternary ammonium base of an n-octyltrimethyl compound.

13. The method according to claim 12, wherein: The molar ratio of the silicon source in terms of SiO2, the aluminum source in terms of Al2O3, the first organic template, the second organic template, the alkali source and water is 1: (0.01-0.20): (0.05-0.80): (0.05-0.80): (0.05-0.50): (8-80); and / or The conditions for crystallization of the mixture include: The crystallization temperature is 120-200°C; and / or The crystallization time is 1 to 15 days.

14. The method according to claim 13, wherein: The molar ratio of the silicon source, calculated as SiO2, the aluminum source, calculated as Al2O3, the first organic template, the second organic template, the alkali source and water is 1: (0.01-0.10): (0.08-0.65): (0.08-0.65): (0.08-0.45): (10-70); and / or The conditions for crystallization of the mixture include: The crystallization temperature is 130-190°C; and / or The crystallization time is 2 to 12 days.

15. The method according to claim 14, wherein The molar ratio of the silicon source in terms of SiO2, the aluminum source in terms of Al2O3, the first organic template, the second organic template, the alkali source and water is 1: (0.02-0.07): (0.10-0.50): (0.10-0.50): (0.10-0.40): (12-60); and / or The conditions for crystallization of the mixture include: The crystallization temperature is 140-180°C; and / or The crystallization time is 3 to 9 days.

16. The method according to claim 12, wherein: The second organic template is at least one selected from cetylpyridinium bromide, tetradecylpyridinium bromide, dodecylpyridinium bromide, cetylpyridinium chloride, tetradecylpyridinium chloride, cetylpyridinium hydroxide, n-octyltrimethylammonium chloride, n-octyltrimethylammonium bromide and n-octyltrimethylammonium hydroxide; The silicon source is selected from at least one of silicic acid, silica gel, silica sol, tetraethyl silicate and water glass; and / or The aluminum source is selected from at least one of aluminum hydroxide, aluminum oxide, aluminate, aluminum salt and tetraalkoxyaluminum; and / or The alkali source is at least one selected from inorganic bases having alkali metals and / or alkaline earth metals as cations.

17. The method according to claim 16, wherein The second organic template is at least one selected from cetylpyridinium bromide, tetradecylpyridinium bromide, dodecylpyridinium bromide, cetylpyridinium chloride, cetylpyridinium hydroxide, n-octyltrimethylammonium chloride and n-octyltrimethylammonium bromide.

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