High-para-methyl-ethylbenzene forming catalyst as well as preparation method and application thereof

Abstract

The invention discloses a high-para-position methyl-ethylbenzene forming catalyst as well as a preparation method and application thereof. The high-para-position methyl-ethylbenzene forming catalyst is obtained by mixing an ammonium type ZSM-5-coated Silicalite-1 core-shell molecular sieve, a binder, an extrusion aid and nitric acid, performing extrusion molding, performing drying I and performing roasting, the ammonium type core-shell molecular sieve is obtained by mixing raw materials containing a silicon source I, an aluminum source, a template agent, alkali, a seed crystal and water, crystallizing I in a closed container, adding a silicon source II, crystallizing II and drying II. Compared with a series of problems of high water-silicon ratio, complex process, environmental pollution and the like existing in a traditional core-shell material synthesis method, the synthesis method has the advantages that the water-silicon ratio of a system is low, the coating effect is good, the process is simple, ammonium exchange is not needed, the obtained catalyst has very high strength, and the silicon-aluminum ratio and the core-shell ratio are adjustable; the catalyst shows high p-methyl ethylbenzene selectivity in the reaction of toluene and ethylation agents (ethanol, ethylene and the like).

Description

Technical Field

[0001] The present application relates to a high para - ethyltoluene forming catalyst, a preparation method thereof and an application thereof, belonging to the technical field of catalytic chemistry. Background Art

[0002] p - Ethyltoluene is an important organic synthesis raw material. Through dehydrogenation and polymerization processes, polymethylstyrene can be obtained, which is widely used in engineering plastics, flame - retardant special resins, and reinforced polyester fibers, etc. p - Ethyltoluene can be prepared by the alkylation reaction of toluene and an ethylating agent (including ethanol, ethylene, etc.). However, since the boiling points of the ethyltoluene isomers obtained are not very different, it is relatively difficult to separate them. Alkylation is a typical acid - catalyzed process. Traditional alkylation catalysts include homogeneous acid catalysts such as AlCl3 and H2SO4. Later, catalytic materials gradually developed to mainly acidic molecular sieves. ZSM - 5 molecular sieve has straight channels and sinusoidal channels. The shape - selectivity of the channels can not only inhibit the occurrence of side reactions but also improve the selectivity to p - ethyltoluene. With the help of its special channel structure and acidity, ZSM - 5 molecular sieve is used as a shape - selective catalyst for acid - catalyzed reactions and is widely used in fine chemical industry, petrochemical industry, environmental protection, etc. However, there are a large number of acidic sites on the pore mouth and outer surface of ZSM - 5 molecular sieve, which makes the para - selective products diffusing out of the pores easily undergo isomerization reactions on the surface, and finally form three isomers in thermodynamic equilibrium. Therefore, it does not have shape - selective catalytic ability itself and needs to be modified.

[0003] The ZSM - 5 molecular sieve can be modified from two aspects: pore structure and acid distribution. The most crucial one is to passivate the acidic sites on the outer surface of the molecular sieve, inhibit the occurrence of side reactions, and change the shape - selectivity of the pores to reactant or product molecules. There are many modification methods for ZSM - 5 molecular sieve, including acid treatment, alkali treatment, impregnation method, steam treatment, ion exchange method, etc. However, most of these methods are not only complex in steps, but also high in preparation cost and poor in repeatability. The coating method (also known as epitaxial growth of an inert shell), since the pores of Silicalite - 1 and ZSM - 5 zeolite can be completely matched, constructing a composite molecular sieve with an acidic core and an inert shell can effectively passivate the acidic sites on the outer surface of the molecular sieve, thus achieving high selectivity.

[0004] The synthesis methods of traditional core-shell materials have many problems such as extremely high requirements for silicon sources, complex processes, low single-kettle output, and poor coating effects, which limit their large-scale industrial production. Farnoosh Goodarzi et al. [Microporous and Mesoporous Mater., 2019, 292: 1387-1811] synthesized an ultrathin Silicalite-1 shell on mesoporous ZSM-5 zeolite by a solid-state steam-assisted method, thereby prolonging the catalyst life. However, this method requires the synthesis of a considerable amount of water vapor, with high energy consumption, and all ZSM-5 samples need to be ammonium-exchanged. LUAN Huimin et al. [Chem. Res. Chinese Universities, 2022, 38(1): 136-140] reported a template-free and solvent-free system, and synthesized core-shell structured ZSM-5@Silicalite-1 zeolite through a strategy of alcohol filling and adding zeolite seeds. However, its preparation process requires ammonium exchange, and its para-selectivity is lower than 90%. Patent CN102259019A designed a composite core-shell molecular sieve, that is, phosphorus is loaded on the surface of ZSM-5 molecular sieve, Silicalite-1 is coated on the outer layer of P-ZSM-5, and rare earth elements are loaded on its outer layer. Although a core-shell molecular sieve with a good shell coverage can be obtained, its preparation process is relatively cumbersome. Patent CN112777609A reported a composite twin-crystal core-shell molecular sieve, which also covers Silicalite-1 on the surface of ZSM-5. However, the water-silica ratio of its shell mother liquor is relatively high, resulting in a large amount of organic wastewater generated during the synthesis process. CN101723401A reported a ZSM-5 / ZSM-5 core-shell zeolite molecular sieve, but its water-silica ratio is relatively high, the process is complex, and ammonium exchange is still required. To sum up, most of the preparation processes of core-shell materials need to be ammonium-exchanged or have a relatively high water-silica ratio to avoid the separate nucleation of silicon sources. Based on this, a controllable synthesis method for ZSM@Silicalite-1 core-shell molecular sieve is urgently needed to be developed. Therefore, constructing an excellent para-ethylmethylbenzene forming catalyst is still a topic worthy of exploration. Summary of the Invention

[0005] The object of the present invention is to develop a controllable synthesis of a core-shell molecular sieve that realizes high para-ethylmethylbenzene selectivity. This synthesis method is not only simple in process, does not require ammonium exchange, has a good coating effect, but also the obtained para-ethylmethylbenzene forming catalyst has many advantages such as high strength, uniform size, adjustable core-shell ratio, and adjustable silicon-aluminum ratio.

[0006] In one aspect of the present application, a high para - ethylmethylbenzene forming catalyst is provided. The high para - ethylmethylbenzene forming catalyst is obtained by mixing an ammonium - type ZSM - 5@Silicalite - 1 core - shell molecular sieve, a binder, an extrusion aid, and nitric acid, extruding into strips, drying I, and calcining.

[0007] The ammonium - type ZSM - 5@Silicalite - 1 core - shell molecular sieve is obtained by mixing raw materials containing a silicon source I, an aluminum source, a template agent, an alkali, seed crystals, and water, crystallizing I in a closed container, then adding a silicon source II, crystallizing II, and drying II.

[0008] Optionally, the silicon source I and the silicon source II are independently selected from at least one of silica sol, water glass, silica gel, tetraethyl orthosilicate, white carbon black, and activated clay.

[0009] Optionally, the aluminum source is selected from at least one of aluminum nitrate, aluminum chloride, aluminum sulfate, sodium meta - aluminate, and aluminum isopropoxide.

[0010] Optionally, the template agent is selected from at least one of cyclohexylamine, n - butylamine, tetrapropylammonium bromide, tetrabutylammonium bromide, tetraethylammonium bromide, tetrabutylammonium hydroxide, 1,6 - hexanediamine, and ethylamine.

[0011] Optionally, the seed crystals are from Silicalite - 1.

[0012] Optionally, the alkali is selected from at least one of ethylenediamine, n - butylamine, cyclohexylamine, diethylamine, triethylamine, ammonia water, and ethylamine.

[0013] Optionally, the mass percentage of the ammonium - type ZSM - 5@Silicalite - 1 core - shell molecular sieve in the high para - ethylmethylbenzene forming catalyst is 55 - 90%;

[0014] The mass percentage of the binder in the high para - ethylmethylbenzene forming catalyst is 10% - 45%;

[0015] The mass percentage of the extrusion aid in the high para - ethylmethylbenzene forming catalyst is 1% - 5%;

[0016] The mass concentration of the nitric acid is 8 - 15%;

[0017] The percentage of the nitric acid in the total dry mass is 0.4 - 1.0.

[0018] Optionally, the microstructure of the ammonium - type ZSM - 5@Silicalite - 1 core - shell molecular sieve is coffin - shaped.

[0019] Optionally, the particle size of the ammonium-form ZSM-5@Silicalite-1 core-shell molecular sieve is 0.4 to 10.0 μm.

[0020] Optionally, the particle size of the ammonium-form ZSM-5@Silicalite-1 core-shell molecular sieve independently selects any value from 0.4 μm, 0.5 μm, 1 μm, 1.5 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm or a range value between any two of the above.

[0021] Optionally, the silica-alumina ratio of the ammonium-form ZSM-5@Silicalite-1 core-shell molecular sieve is 20 to 1000.

[0022] Optionally, the silica-alumina ratio of the ammonium-form ZSM-5@Silicalite-1 core-shell molecular sieve independently selects any value from 20, 50, 100, 200, 300, 400, 500, 600, 700, 800, 900, 1000 or a range value between any two of the above.

[0023] In another aspect of the present application, a preparation method of the above-mentioned high-para ethylbenzene forming catalyst is provided, and the preparation method includes: mixing the ammonium-form ZSM-5@Silicalite-1 core-shell molecular sieve, binder, extrusion aid and nitric acid, extruding into a strip, drying I, and calcining.

[0024] The synthesis method of the ammonium-form ZSM-5@Silicalite-1 core-shell molecular sieve includes: mixing raw materials containing silicon source I, aluminum source, template agent, alkali, seed crystal and water, crystallizing I in a closed container, then adding silicon source II, and crystallizing II, and obtaining it after drying II.

[0025] As a specific implementation manner, the synthesis method of the ammonium-form ZSM-5@Silicalite-1 core-shell molecular sieve includes: mixing raw materials containing silicon source I, aluminum source, water, template agent, seed crystal and alkali, crystallizing I in a closed container, cooling the reaction kettle with tap water, then adding silicon source II, mixing evenly, and crystallizing II, and drying to obtain the ZSM-5@Silicalite-1 core-shell molecular sieve.

[0026] Optionally, in the synthesis method, the molar ratio of aluminum element to silicon element is 0.001 to 0.05, wherein the molar amount of aluminum element is based on the molar amount of aluminum element in the aluminum source, and the molar amount of silicon element is based on the total molar amount of silicon element in the silicon source I and the silicon source II.

[0027] Optionally, the ratio of the molar amount of the aluminum element to the molar amount of the silicon element is independently selected from any value of 0.001, 0.0016, 0.003, 0.005, 0.006, 0.01, 0.02, 0.03, 0.04, 0.05 or a range value between any two of the above.

[0028] Optionally, the ratio of the molar amount of the water to the molar amount of the silicon element is 5 to 100, wherein the molar amount of the silicon element is based on the total molar amount of the silicon element in the silicon source I and the silicon source II.

[0029] Optionally, the ratio of the molar amount of the water to the molar amount of the silicon element is independently selected from any value of 5, 10, 15, 20, 30, 40, 50, 60, 70, 80, 90, 100 or a range value between any two of the above.

[0030] Optionally, the ratio of the molar amount of the template agent to the molar amount of the silicon element is 0.02 to 0.4, wherein the molar amount of the silicon element is based on the total molar amount of the silicon element in the silicon source I and the silicon source II.

[0031] Optionally, the ratio of the molar amount of the template agent to the molar amount of the silicon element is independently selected from any value of 0.02, 0.04, 0.05, 0.10, 0.20, 0.25, 0.30, 0.40 or a range value between any two of the above.

[0032] Optionally, the ratio of the mass of the seed crystal to the total mass of the silicon source I and the silicon source II is 0.00002 to 0.02, wherein the mass of the seed crystal is based on the mass of silicon dioxide in the seed crystal, and the total mass of the silicon source I and the silicon source II is based on the total mass of silicon dioxide in the silicon source I and the silicon source II.

[0033] Optionally, the ratio of the mass of the seed crystal to the total mass of the silicon source I and the silicon source II is independently selected from any value of 0.00002, 0.00005, 0.0001, 0.0004, 0.0005, 0.001, 0.002, 0.005, 0.006, 0.01, 0.02 or a range value between any two of the above.

[0034] Optionally, the size of the seed crystal is 100 to 800 nm.

[0035] Optionally, the size of the seed crystal is independently selected from any value of 100 nm, 200 nm, 300 nm, 400 nm, 500 nm, 600 nm, 700 nm, 800 nm or a range value between any two of the above.

[0036] Optionally, the molar ratio of the base to the silicon element is 0.02 to 0.40, where the molar amount of the silicon element is based on the total molar amount of the silicon element in the silicon source I and the silicon source II.

[0037] Optionally, the molar ratio of the base to the silicon element independently selects any value from 0.02, 0.04, 0.05, 0.06, 0.10, 0.20, 0.30, 0.40 or the range value between any two of the above.

[0038] Optionally, the molar ratio of the silicon element in the silicon source I to the silicon element in the silicon source II is 0.1 to 10.

[0039] Optionally, the molar ratio of the silicon element in the silicon source I to the silicon element in the silicon source II independently selects any value from 0.1, 0.5, 1, 1.5, 1.6, 2, 2.3, 3, 4, 5, 6, 7, 8, 9, 10 or the range value between any two of the above.

[0040] Optionally, the temperature of the crystallization I is 100 to 200 °C; the time of the crystallization I is 2 to 96 h.

[0041] Optionally, the temperature of the crystallization I independently selects any value from 100 °C, 110 °C, 120 °C, 130 °C, 140 °C, 150 °C, 160 °C, 170 °C, 180 °C, 190 °C, 200 °C or the range value between any two of the above.

[0042] Optionally, the time of the crystallization I independently selects any value from 2 h, 4 h, 8 h, 16 h, 24 h, 32 h, 48 h, 64 h, 72 h, 96 h or the range value between any two of the above.

[0043] Optionally, the temperature of the crystallization II is 100 to 200 °C; the time of the crystallization II is 2 to 96 h.

[0044] Optionally, the temperature of the crystallization II independently selects any value from 100 °C, 110 °C, 120 °C, 130 °C, 140 °C, 150 °C, 160 °C, 170 °C, 180 °C, 190 °C, 200 °C or the range value between any two of the above.

[0045] Optionally, the time of the crystallization II independently selects any value from 2 h, 4 h, 8 h, 12 h, 16 h, 24 h, 32 h, 64 h, 96 h or the range value between any two of the above.

[0046] Optionally, the temperature of the drying II is 60 to 200 °C; the time of the drying II is 6 to 24 h.

[0047] Optionally, the temperature of the second drying is independently selected from any value of 60°C, 100°C, 120°C, 150°C, 200°C or a range value between any two of the above.

[0048] Optionally, the time of the second drying is independently selected from any value of 6h, 12h, 18h, 24h or a range value between any two of the above.

[0049] Optionally, after the second crystallization and before the second drying, washing and solid-liquid separation are also required.

[0050] Optionally, the binder is selected from at least one of alumina, silica, and clay;

[0051] The extrusion aid is selected from at least one of sesbania powder, cellulose, and starch.

[0052] Optionally, the temperature of the second drying is 100-150°C; the time of the second drying is 6-24h.

[0053] Optionally, the temperature of the second drying is independently selected from any value of 100°C, 110°C, 120°C, 130°C, 140°C, 150°C or a range value between any two of the above.

[0054] Optionally, the time of the second drying is independently selected from any value of 6h, 12h, 18h, 24h or a range value between any two of the above.

[0055] Optionally, the temperature of the calcination is 300-600°C, the time of the calcination is 4-8h, and the heating rate of the calcination is 1-5°C / h.

[0056] Optionally, the heating rate from 150°C to 300°C is not higher than 5°C / h.

[0057] Optionally, the temperature of the calcination is independently selected from any value of 300°C, 400°C, 500°C, 600°C or a range value between any two of the above.

[0058] Optionally, the time of the calcination is independently selected from any value of 4h, 5h, 6h, 7h, 8h or a range value between any two of the above.

[0059] Optionally, the ammonium-type ZSM-5@Silicalite-1 core-shell molecular sieve does not need to be subjected to ammonium exchange, and the H-type ZSM-5@Silicalite-1 core-shell molecular sieve obtained by extrusion molding and then calcination can be directly used for reaction evaluation.

[0060] Optionally, the ammonium-type ZSM-5@Silicalite-1 core-shell molecular sieve raw powder, binder, and extrusion aid are mixed evenly in a certain proportion, and then an appropriate amount of dilute nitric acid solution is added. After extrusion molding and drying at room temperature and then drying in an oven, the ammonium-type high p-ethyltoluene shaped catalyst is obtained. The ammonium-type high p-ethyltoluene shaped catalyst is calcined to obtain an H-type high p-ethyltoluene shaped catalyst, which is used for the reaction of toluene with an ethylating agent (such as ethanol, ethylene, etc.).

[0061] As a specific embodiment, the high p-ethyltoluene shaped catalyst is prepared by mixing, molding, and drying an ammonium-type ZSM-5@Silicalite-1 core-shell molecular sieve, binder, extrusion aid, and dilute nitric acid; the ammonium-type ZSM-5@Silicalite-1 core-shell molecular sieve is prepared by configuring a mother liquor from a silicon source, aluminum source, template agent, base, seed crystal, and water, and hydrothermally crystallizing at a certain temperature using an innovative step-by-step synthesis method.

[0062] A preparation method of a high p-ethyltoluene shaped catalyst solves the above technical problems by using appropriate raw materials and finely adjusting the composition of the raw materials and adopting a hydrothermal crystallization method. The preparation process of the catalyst at least includes the following steps: configuring a mother liquor from a silicon source, aluminum source, template agent, base, seed crystal, and water, hydrothermally crystallizing at a certain temperature using an innovative step-by-step synthesis method, and drying to obtain an ammonium-type ZSM-5@Silicalite-1 core-shell molecular sieve raw powder. The above ammonium-type ZSM-5@Silicalite-1 core-shell molecular sieve is mixed with a binder, extrusion aid, and dilute nitric acid, extruded into shape, and dried to obtain the high p-ethyltoluene shaped catalyst.

[0063] In another aspect of the present application, there is provided an application of the above high p-ethyltoluene shaped catalyst or the high p-ethyltoluene shaped catalyst obtained according to the above preparation method in the reaction of toluene with an ethylating agent, and the application includes: contacting a raw material containing toluene and an ethylating agent with the activated high p-ethyltoluene shaped catalyst and reacting.

[0064] As a specific embodiment, there is provided an application of the above high p-ethyltoluene shaped catalyst or the high p-ethyltoluene shaped catalyst prepared by the above preparation method, as a catalyst for the reaction of toluene with an ethylating agent (such as ethanol, ethylene, etc.), at least including the following steps:

[0065] The H-type high p-ethyltoluene shaped catalyst is reductively activated in an air atmosphere, and after activation, the temperature is lowered to the reaction temperature, and then the reaction raw material is contacted with the high p-ethyltoluene shaped catalyst and reacted.

[0066] Optionally, the activation is carried out under an air atmosphere condition, the activation temperature is 400-550°C, and the activation time is 1-10 h.

[0067] Optionally, the activation temperature is independently selected from any value of 400 °C, 450 °C, 500 °C, 550 °C or a range value between any two of the above.

[0068] Optionally, the activation time is independently selected from any value of 1 h, 2 h, 3 h, 4 h, 5 h, 6 h, 7 h, 8 h, 9 h, 10 h or a range value between any two of the above.

[0069] Optionally, the mass space velocity of the reaction is 0.4 - 1 h -1 。

[0070] Optionally, the mass space velocity of the reaction is independently selected from any value of 0.4 h -1 、0.5 h -1 、0.6 h -1 、0.7 h -1 、0.8 h -1 、0.9 h -1 、1.0 h -1 or a range value between any two of the above.

[0071] Optionally, in the raw material, the molar ratio of toluene to the ethylating agent is 2 - 10.

[0072] Optionally, in the raw material, the molar ratio of toluene to the ethylating agent is independently selected from any value of 2 h, 3 h, 4 h, 5 h, 6 h, 7 h, 8 h, 9 h, 10 h or a range value between any two of the above.

[0073] Optionally, the ethylating agent is selected from at least one of ethanol and ethylene.

[0074] Optionally, the reaction temperature is 200 - 400 °C.

[0075] Optionally, the reaction temperature is independently selected from any value of 200 °C, 250 °C, 300 °C, 350 °C, 365 °C, 400 °C or a range value between any two of the above.

[0076] Optionally, the reaction pressure is 0.1 MPa.

[0077] The beneficial effects that can be produced by this application include:

[0078] In view of the many problems existing in the traditional preparation method of ZSM-5@Silicalite-1 core-shell molecular sieve, such as complex process, poor coating effect, low single-kettle output, extremely high requirements for silicon source, and being not conducive to large-scale industrial production, a step-by-step synthesis method with advantages of simple operation, good coating effect, cheap and easily available raw materials, and good repeatability is proposed. The prepared core-shell molecular sieve has high strength, uniform size, adjustable core-shell ratio and adjustable silicon-aluminum ratio, and is suitable for industrial scale-up synthesis. Description of the Drawings

[0079] Figure 1 It is the X-ray diffraction pattern of the sample of Example 1.

[0080] Figure 2 It is the scanning electron microscope photograph of the sample of Example 1, and the scale bar is 10 μm.

[0081] Figure 3 It is the X-ray photoelectron spectrum of the sample of Example 1.

[0082] Figure 4 It is the scanning electron microscope photograph of the sample of Example 2, and the scale bar is 10 μm.

[0083] Figure 5 It is the evaluation of the performance of the para-selective ethylbenzene forming catalyst prepared from the sample of Example 1 in the shape-selective alkylation reaction of toluene and ethanol.

[0084] Figure 6 It is the evaluation of the performance of the para-selective ethylbenzene forming catalyst prepared from the sample of Example 2 in the shape-selective alkylation reaction of toluene and ethanol.

[0085] Figure 7 It is the scanning electron microscope photograph of the sample of Comparative Example 1, and the scale bar is 10 μm.

[0086] Figure 8 It is the evaluation of the performance of the para-selective ethylbenzene forming catalyst prepared from the sample of Comparative Example 1 in the shape-selective alkylation reaction of toluene and ethanol. Detailed Embodiments

[0087] The present application will be described in detail below with reference to the embodiments, but the present application is not limited to these embodiments.

[0088] Except for the Silicalite-1 seeds, unless otherwise specified, the raw materials and reagents in the embodiments of the present application are all purchased through commercial channels.

[0089] The analysis methods in the embodiments of the present application are as follows:

[0090] The crystal phase and relative crystallinity are analyzed using an X-ray diffractometer, and the instrument model is SmartLab9.

[0091] Morphological analysis was carried out using a scanning electron microscope, and the instrument model was SU1510.

[0092] The elemental content was analyzed using a quasi-in-situ X-ray photoelectron spectrometer, and the instrument model was Escalab250.

[0093] Example 1

[0094] The raw materials used are as follows:

[0095] A. Fumed silica (Evonik Degussa A380)

[0096] B. Aqueous ethylamine solution (Aladdin reagent)

[0097] C. Aluminum chloride hexahydrate (Tianjin Kemiou Chemical Reagent Co., Ltd.)

[0098] D. Tetrapropylammonium hydroxide (TPAOH, Shanghai Cairui Chemical Co., Ltd.)

[0099] E. Silicalite-1 liquid seed (Seed, size 300 nm)

[0100] The molar composition of the raw material mixture was: SiO2 / Al2O3 = 360, H2O / SiO2 = 30, TPAOH / SiO2 = 0.04, ethylamine / SiO2 = 0.10, Seed / SiO2 = 0.0004 (mass ratio). The aqueous ethylamine solution, TPAOH, aluminum chloride, seed, deionized water, and 75 wt% fumed silica were added to the reaction kettle, stirred evenly, and then placed in the crystallization kettle. Crystallization was carried out dynamically at 170 °C for 48 h; after the crystallization was completed, the reaction was quenched with tap water, the remaining 25 wt% fumed silica was added, and crystallization was continued at 170 °C for 24 h. Then it was cooled, washed, and dried overnight in a constant-temperature oven at 120 °C to obtain the molecular sieve raw powder, and its solid yield could reach more than 90%. Figure 1 For the X-ray diffraction pattern of the obtained ZSM-5@Silicalite-1 core-shell molecular sieve, it can be seen that it has a typical MFI topological structure, relatively high crystallinity and no other impurity phases. Figure 2 [[ID=#31]]For the scanning electron microscope photograph of this sample, it has a coffin-like structure, with uniform size (~6 μm), regular morphology, and good dispersion. Figure 3 For the X-ray photoelectron spectrum of this sample, the results show that it contains a very small amount of aluminum on its surface, while the XRF results show that the bulk phase SiO2 / Al2O3 is 293, proving the successful preparation of the core-shell material.

[0101] Example 2:

[0102] The raw materials used are as follows:

[0103] A. Solid silica gel

[0104] B. Ammonia water

[0105] C. Aluminum nitrate nonahydrate

[0106] D. Tetrapropylammonium bromide (TPAOH)

[0107] E. Silicalite-1 liquid seed (Seed, size 200 nm)

[0108] The molar composition of the raw material mixture is: SiO2 / Al2O3 = 600, TPAOH / SiO2 = 0.05, H2O / SiO2 = 20, ammonia water / SiO2 = 0.04, Seed / SiO2 = 0.006 (mass ratio). Aluminum nitrate, 62.5 wt% solid silica gel, deionized water, seed, ammonia water and TPAOH were added to the reaction kettle, stirred evenly and then placed in the crystallization kettle, and crystallized dynamically at 170 °C for 24 h; after the crystallization was completed, the remaining 37.5 wt% solid silica gel was added, and after continuing to crystallize at 170 °C for 24 h, it was cooled to room temperature, washed with deionized water until neutral, and dried overnight in a constant temperature oven at 120 °C to obtain the molecular sieve raw powder. Figure 4 This is the scanning electron microscope photograph of the obtained ZSM-5@Silicalite-1 core-shell material, which has uniform size (∼4 μm), regular morphology and good dispersion.

[0109] Examples 3-6:

[0110] Examples 3-6 were synthesized to obtain core-shell molecular sieves according to the synthesis ratios and conditions in Table 1 by a method and steps similar to those in Example 1. See Table 1 for details.

[0111] Table 1

[0112]

[0113] Example 6

[0114] The ZSM-5@Silicalite-1 core-shell molecular sieve obtained in Example 1 was extruded into pellets for use in the toluene and ethanol alkylation reaction process. Al2O3 was selected as the binder, and the dry basis mass percentage of the molecular sieve to the binder was 85%:15%. Then, 2% of the total dry basis mass of the talc powder was added, and the mixture was stirred evenly. Then, an appropriate amount of 10% dilute nitric acid solution (nitric acid accounted for 0.8% of the total dry basis mass) was added. After extrusion into pellets, it was dried at 120 °C for 8 h, calcined at 540 °C at a heating rate of 2 °C / h for 6 h, and crushed into 20-40 mesh. The reaction performance evaluation of the catalyst was carried out on a fixed-bed reaction device. The catalyst loading was 2.0 g. The catalyst was pretreated at 450 °C for 1 h in an air atmosphere. The reaction temperature was 365 °C, the reaction pressure was 0.1 MPa, the molar ratio of toluene to ethanol in the feed was 7, and the space velocity was 0.5 h -1, analyzed using an Agilent GC8890 gas chromatograph with an FID detector. The reaction results are as Figure 5 shown. As can be seen from the figure, the selectivity for p-ethyltoluene (P-ET) during the stable period reaches over 93%.

[0115] P-ET selectivity = (amount of P-ET produced / amount of methyl ethylbenzene produced) × 100%

[0116] Example 7

[0117] The ZSM-5@Silicalite-1 core-shell molecular sieve obtained in Example 2 was extruded into pellets for use in the toluene and ethanol alkylation reaction process. Al2O3 was selected as the binder, and the mass percentage of the molecular sieve to the dry binder was 80%:20%. Add talc powder (3% of the total dry mass), mix evenly, and then add an appropriate amount of 10% dilute nitric acid solution (nitric acid accounts for 0.6% of the total dry mass). After extrusion molding, it was dried at 100 °C for 10 h, calcined at 3 °C / h to 450 °C for 6 h, and crushed into 20-40 mesh. The reaction performance evaluation of the catalyst was carried out on a fixed-bed reaction device. The catalyst loading was 2.0 g. The catalyst was pretreated at 450 °C for 1 h in an air atmosphere. The reaction temperature was 365 °C, the reaction pressure was 0.1 MPa, the molar ratio of toluene to ethanol in the feed was 7, and the space velocity was 0.5 h -1 , analyzed using an Agilent GC8890 gas chromatograph with an FID detector. The reaction results are as Figure 6 shown. As can be seen from the figure, the selectivity for p-ethyltoluene (P-ET) during the stable period can reach about 90%.

[0118] P-ET selectivity = (amount of P-ET produced / amount of methyl ethylbenzene produced) × 100%

[0119] Comparative Example 1

[0120] The raw materials used are as follows:

[0121] A. Colloidal silica

[0122] B. Aqueous solution of n-butylamine (Aladdin reagent)

[0123] C. Aluminum chloride hexahydrate (Tianjin Kemiou Chemical Reagent Co., Ltd.)

[0124] D. Tetrabutylammonium hydroxide (TBAOH, Shanghai Cairui Chemical Co., Ltd.)

[0125] E. Silicalite-1 liquid seeds (Seed, size 300 nm)

[0126] The molar composition of the raw material mixture is: SiO2 / Al2O3 = 320, H2O / SiO2 = 25, TPAOH / SiO2 = 0.10, ethylamine / SiO2 = 0.20, Seed / SiO2 = 0.0001 (mass ratio). An aqueous solution of ethylamine, TPAOH, aluminum chloride, seed crystals, deionized water and all silica are added to a reaction kettle, stirred evenly and then placed in a crystallization kettle, and crystallized dynamically at 170 °C for 48 h; after the crystallization is completed, the reaction is quenched with tap water. It is washed with deionized water until neutral and dried overnight in a constant temperature oven at 120 °C to obtain the molecular sieve raw powder. Figure 7 This is the scanning electron microscope photo of the obtained ZSM-5 molecular sieve, with uniform size (~7 μm), regular morphology and good dispersion.

[0127] Comparative Example 2

[0128] The catalyst obtained in Comparative Example 1 was extruded into pellets and used in the alkylation reaction of toluene and ethanol. Al2O3 was selected as the binder, and the mass percentage of the molecular sieve to the binder on a dry basis was 87%:13%. Sucrose powder (accounting for 3% of the total dry basis mass) was added, mixed evenly, and then an appropriate amount of 10% dilute nitric acid solution (nitric acid accounting for 0.4% of the total dry basis mass) was added. After extrusion into pellets, it was dried at 110 °C for 8 h, calcined at 420 °C with a heating rate of 4 °C / h for 5 h, and crushed into 20-40 mesh. The reaction performance evaluation of the catalyst was carried out on a fixed-bed reaction device. The catalyst loading was 2.0 g. The catalyst was pretreated at 450 °C for 1 h in an air atmosphere. The reaction temperature was 360 °C, the reaction pressure was 0.1 MPa, the molar ratio of toluene to ethanol in the feed was 5, and the space velocity was 0.5 h -1 , and analyzed using an Agilent GC8890 gas chromatograph with an FID detector. The reaction results are as Figure 8 shown. It can be seen from the figure that the selectivity of p-ethyltoluene (P-ET) in the stable period can reach about 68%, which is much lower than the catalytic performance of the sample prepared by the stepwise synthesis method.

[0129] P-ET selectivity = (amount of P-ET produced / amount of methyl ethylbenzene produced) × 100%

[0130] As mentioned above, only several embodiments of the present application are described, and it does not impose any form of limitation on the present application. Although the present application is disclosed with preferred embodiments, it is not intended to limit the present application. Any person skilled in the art, without departing from the scope of the technical solution of the present application, makes some changes or modifications using the disclosed technical content, which are equivalent to equivalent implementation cases and all fall within the scope of the technical solution.

Claims

1. A high para - ethylmethylbenzene forming catalyst, characterized in that, the high para - ethylmethylbenzene forming catalyst is obtained by mixing ammonium - type ZSM - 5@Silicalite - 1 core - shell molecular sieve, binder, extrusion aid and nitric acid, extruding into strips, drying I, and calcining; the ammonium - type ZSM - 5@Silicalite - 1 core - shell molecular sieve is obtained by mixing raw materials containing silicon source I, aluminum source, template agent, alkali, seed crystal, and water, crystallizing I in a closed container, then adding silicon source II, crystallizing II, and drying II.

2. The high para - ethylmethylbenzene forming catalyst according to claim 1, characterized in that, the silicon source I and silicon source II are independently selected from at least one of silica sol, water glass, silica gel, tetraethyl orthosilicate, white carbon black, activated clay; the aluminum source is selected from at least one of aluminum nitrate, aluminum chloride, aluminum sulfate, sodium metaaluminate, aluminum isopropoxide; the template agent is selected from at least one of cyclohexylamine, n - butylamine, tetrapropylammonium bromide, tetrabutylammonium bromide, tetraethylammonium bromide, tetrabutylammonium hydroxide, 1,6 - hexanediamine, ethylamine; the seed crystal is from Silicalite - 1; the alkali is selected from at least one of ethylenediamine, n - butylamine, cyclohexylamine, diethylamine, triethylamine, ammonia water, ethylamine.

3. The high para - ethylmethylbenzene forming catalyst according to claim 1, characterized in that, the mass percentage of the ammonium - type ZSM - 5@Silicalite - 1 core - shell molecular sieve in the high para - ethylmethylbenzene forming catalyst is 55 - 90%; the mass percentage of the binder in the high para - ethylmethylbenzene forming catalyst is 10% - 45%; the mass percentage of the extrusion aid in the high para - ethylmethylbenzene forming catalyst is 1% - 5%; the mass concentration of the nitric acid is 8 - 15%; the percentage of the nitric acid in the total dry mass is 0.4 - 1.

0.

4. The high para - ethylmethylbenzene forming catalyst according to claim 1, characterized in that, the microstructure of the ammonium - type ZSM - 5@Silicalite - 1 core - shell molecular sieve is coffin - shaped; the particle size of the ammonium - type ZSM - 5@Silicalite - 1 core - shell molecular sieve is 0.4 - 10.0 μm; the silicon - aluminum ratio of the ammonium - type ZSM - 5@Silicalite - 1 core - shell molecular sieve is 20 - 1000.

5. A preparation method of the high para - ethylmethylbenzene forming catalyst according to any one of claims 1 - 4, characterized in that, the preparation method includes: mixing ammonium - type ZSM - 5@Silicalite - 1 core - shell molecular sieve, binder, extrusion aid and nitric acid, extruding into strips, drying I, and calcining; the synthesis method of the ammonium - type ZSM - 5@Silicalite - 1 core - shell molecular sieve includes: mixing raw materials containing silicon source I, aluminum source, template agent, alkali, seed crystal, and water, crystallizing I in a closed container, then adding silicon source II, crystallizing II, and drying II.

6. The preparation method according to claim 5, characterized in that, In the synthesis method, the molar ratio of aluminum element to silicon element is 0.001 - 0.

05. Among them, the molar amount of aluminum element is based on the molar amount of aluminum element in the aluminum source, and the molar amount of silicon element is based on the total molar amount of silicon element in the silicon source I and the silicon source II; The molar ratio of water to silicon element is 5 - 100. Among them, the molar amount of silicon element is based on the total molar amount of silicon element in the silicon source I and the silicon source II; The molar ratio of the template agent to silicon element is 0.02 - 0.

4. Among them, the molar amount of silicon element is based on the total molar amount of silicon element in the silicon source I and the silicon source II; The mass ratio of the seed crystal to the total mass of the silicon source I and the silicon source II is 0.00002 - 0.

02. Among them, the mass of the seed crystal is based on the mass of silicon dioxide in the seed crystal, and the total mass of the silicon source I and the silicon source II is based on the total mass of silicon dioxide in the silicon source I and the silicon source II; Preferably, the size of the seed crystal is 100 - 800 nm; The molar ratio of the base to silicon element is 0.02 - 0.

40. Among them, the molar amount of silicon element is based on the total molar amount of silicon element in the silicon source I and the silicon source II; The molar ratio of the silicon element in the silicon source I to the silicon element in the silicon source II is 0.1 - 10.

7. The preparation method according to claim 6, wherein, The temperature of the first crystallization is 100 - 200 °C; the time of the first crystallization is 2 - 96 h; The temperature of the second crystallization is 100 - 200 °C; the time of the second crystallization is 2 - 96 h; The temperature of the second drying is 60 - 200 °C; the time of the second drying is 6 - 24 h. After the second crystallization and before the second drying, washing and solid-liquid separation are also required; Preferably, the binder is selected from at least one of alumina, silica, and clay; The extrusion aid is selected from at least one of sesbania powder, cellulose, and starch; The temperature of the first drying is 100 - 150 °C; the time of the first drying is 6 - 24 h; The temperature of the calcination is 300 - 600 °C, the time of the calcination is 4 - 8 h, and the heating rate of the calcination is 1 - 5 °C / h.

8. Use of the high-para methyl ethyl benzene forming catalyst according to any one of claims 1 to 4 or the high-para methyl ethyl benzene forming catalyst obtained by the preparation method according to any one of claims 5 to 7 in the reaction of toluene with an ethylation agent, characterized in that, The application includes: contacting a raw material containing toluene and an ethylating agent with an activated high p - xylene - ethylbenzene forming catalyst and reacting.

9. The application according to claim 8, wherein, The activation is carried out under an air atmosphere condition, the temperature of the activation is 400 - 550 °C, and the time of the activation is 1 - 10 h.

10. The application according to claim 8, wherein, The mass space velocity of the reaction is 0.4 to 1 h -1 ; In the raw material, the molar ratio of toluene to the ethylating agent is 2 - 10; The ethylating agent is selected from at least one of ethanol and ethylene; The temperature of the reaction is 200 - 400 °C.

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