A multi-level porous nanocapsule catalyst and its preparation method and method for converting butadiene

Abstract

The invention discloses a multi-level porous nano-capsule catalyst and a preparation method thereof and a method for converting butadiene, the catalyst and its preparation method, the catalyst includes a core layer and a shell layer, the core layer is ZnZr / Si-Beta, the shell layer is Y / Si-Beta, and the preparation method of the catalyst includes the following steps: Step one: dissolving a Zn source and a Zr source in deionized water in proportion, stirring for 0.1-1h to form a solution one, and then adding a seed crystal Si-Beta to the solution one; Step two: continuously stirring the above-mentioned mixed suspension for 0.5-5h, then evaporating and drying, roasting, and obtaining a ZnZr / Si-Beta product. The multi-level porous nano-capsule catalyst and its preparation method and the method for converting butadiene, using the catalyst provided by the present invention can directly convert 80% ethanol aqueous solution into butadiene, not only can the synthesis cycle be shortened and the use of hydrofluoric acid to avoid polluting the environment can be avoided, but also a multi-level porous nano-structure molecular sieve can be obtained, thereby improving the ethanol conversion rate and butadiene selectivity.

Description

Technical Field

[0001] The invention relates to the technical field of catalyst preparation, in particular to a multi-level porous nano-capsule catalyst and a preparation method thereof and a method for converting butadiene. Background Art

[0002] Butadiene is an important industrial monomer, commonly used in the production of various styrene rubbers, tires, polymers and other chemicals. It is mainly derived from the co-products of ethylene and propylene produced by thermal cracking of naphtha steam. In recent years, the cheap supply of shale gas has led to the shift of the production raw materials of ethylene and propylene from naphtha to ethane and propane, resulting in a shortage of butadiene. Ethanol, as an important renewable carbon source, can be produced through biomass fermentation and catalytic conversion of synthesis gas. Therefore, directly converting ethanol into butadiene can not only alleviate the contradiction of butadiene supply and demand, but also reduce a series of environmental problems caused by excessive dependence on fossil resources.

[0003] In the direct conversion of ethanol to butadiene, high-purity ethanol with a purity higher than 98% is often used to produce butadiene. However, ethanol and water can form an azeotropic mixture, and the preparation of high-purity ethanol requires high energy consumption. At the same time, the production of 80% ethanol aqueous solution has been industrialized; the direct conversion of 80% ethanol aqueous solution to butadiene has broad development prospects. However, when the water content in the ethanol raw material is higher than 5%, the catalytic activity and butadiene selectivity of the catalyst are significantly reduced. Therefore, the development of new and efficient catalysts for direct conversion of ethanol aqueous solution to butadiene is of great significance to increasing butadiene production and large-scale production.

[0004] The catalytic systems currently developed for direct conversion of ethanol-water solution to butadiene mainly include Zn-Zr-Si, Zn-Mg-Si, Zn-Hf-Si and Zn-La-Zr-Si catalytic systems. Among them, the water resistance of the ZnO / MgO-SiO2 catalyst is determined by the ratio of MgO and SiO2. The chemical adsorption of water molecules mainly occurs on the active centers containing Mg, thereby inhibiting the formation of CC coupling products. When the ratio of MgO and SiO2 is 1:1, the ethanol conversion rate is 36.6% and the selectivity of butadiene is 59.7% (Applied Catalysis A: General, 2021, Vol. 616, p. 118081). The number and strength of the Lewis acid sites of the ZnLaZrSi catalyst depend on the choice of silica carrier, which has a significant effect on the butadiene selectivity and yield. The ZnLaZr-Si-Beta catalyst showed an ethanol conversion rate of 36.7% and a 1,3-butadiene selectivity of 50.8% in the direct conversion of 80% ethanol aqueous solution to 1,3-butadiene, but the acetaldehyde selectivity was 19.9%. The main reason is that water molecules adsorbed onto the Lewis acid sites of the catalyst, inhibiting the occurrence of the aldol condensation reaction, while the formation rate of acetaldehyde did not change significantly, resulting in a large amount of acetaldehyde accumulation (ACSSustainableChemistry&Engineering, 2020, Vol. 8, pp. 16600-16611). In comparison, the ZnZr / Si-Beta catalytic system has great development potential for the direct conversion of ethanol aqueous solution to butadiene, but the water molecules have a significant effect on the Lewis acid active sites, resulting in low ethanol conversion and butadiene selectivity.

[0005] In the direct conversion of ZnZr / Si-Beta catalyst to 1,3-butadiene in 80% ethanol aqueous solution, water molecules significantly inhibit the catalytic activity of Lewis acid sites, resulting in a large accumulation of acetaldehyde intermediates. Y species, due to its large ionic radius, easily interacts with silanol to form Lewis acid sites with strong water resistance. Although ZnY / Si-Beta catalyst has strong water resistance, the strong interaction between Y and Zn species gives the catalyst a strong CC coupling ability, resulting in the condensation of acetaldehyde and crotonaldehyde to form byproducts such as acetone and triene. In order to overcome the problem of strong interaction between Zn and Y, a capsule structure catalyst was constructed with ZnZr / Si-Beta as the core layer and Y / Si-Beta as the shell layer. Y / Si-Beta has strong water resistance and can inhibit the influence of water molecules on the active center. At the same time, the shell layer Y / Si-Beta with strong water resistance can strengthen the aldol condensation reaction to produce crotyl alcohol, which is then dehydrated to form butadiene. Therefore, the construction of ZnZr / Si-Beta@Y / Si-Beta capsule catalyst can effectively strengthen the aldol condensation reaction, thereby improving the ethanol conversion rate and butadiene selectivity.

[0006] Therefore, we propose a multi-level porous nanocapsule catalyst and a preparation method thereof and a method for converting butadiene to solve the above-mentioned problems. Summary of the invention

[0007] The purpose of the present invention is to provide a multi-level porous nanocapsule catalyst and a preparation method thereof and a method for converting butadiene, and its purpose is to provide a catalyst that can catalyze the direct conversion of ethanol aqueous solution to butadiene and can significantly improve the ethanol conversion rate and butadiene selectivity.

[0008] To achieve the above object, the present invention provides the following technical solution: a multi-level porous nanocapsule catalyst and a preparation method thereof, wherein the catalyst comprises a core layer and a shell layer, wherein the core layer is ZnZr / Si-Beta and the shell layer is Y / Si-Beta, and the preparation method of the catalyst comprises the following steps:

[0009] Step 1: Dissolve the Zn source and the Zr source in deionized water in proportion, stir for 0.1-1h to form solution 1, and then add the seed crystal Si-Beta to solution 1;

[0010] Step 2: Stir the mixed suspension for 0.5-5 hours, evaporate and dry, and calcine to obtain a ZnZr / Si-Beta product;

[0011] Step 3: According to the molar ratio of template to Si source of 0.05-0.25, a certain amount of template and silicon source are respectively impregnated on the product obtained in step 2, and ultrasonic and dried to obtain a ZnZr / Si-Beta product modified with template and silicon source;

[0012] Step 4: Add the remaining template and Si source into deionized water, add alkali source at a molar ratio of alkali source to Si source of 0.1-0.3, stir for 0.5-2h, then add Y source at a Y / Si molar ratio of 0.5-1.5 and continue stirring for 1-4h;

[0013] Step 5: Add the product obtained in step 3 to step 4 and continue stirring for 1-3 hours, then dry and grind to obtain dry glue;

[0014] Step 6: Add the dry glue obtained in step 5 to a polytetrafluoroethylene liner with a jacket, add deionized water in a certain mass ratio to the jacket, perform crystallization, washing, drying, and calcination to obtain a multi-level porous nano ZnZr / Si-Beta@Y / Si-Beta capsule catalyst.

[0015] Preferably, in step 1, the Zn source is selected from one of zinc acetate, zinc nitrate and zinc chloride; the Zr source is selected from one of zirconium oxynitrate, zirconium n-propoxide, zirconium chloride and zirconium sulfate;

[0016] The molar ratio of the Zn source to the Zr source is 0.01-0.1 for Zn / Si and 0.1-0.6 for Zr / Si.

[0017] Preferably, the evaporation drying condition in step 2 is drying at 80-120° C. for 12-24 h; and the roasting condition is roasting at 300-550° C. for 4-10 h.

[0018] Preferably, in step 3, the template agent is one of tetrapropylammonium hydroxide, tetrapropylammonium bromide, tetraethylammonium hydroxide and diethylamine; the silicon source is one of tetraethyl orthosilicate, fumed silica and silica sol;

[0019] The certain amount of the template agent refers to a loading amount of the template agent of 2%-10%, and a loading amount of the Si source of 1%-6%;

[0020] The ultrasonic condition in the step 3 is ultrasonication at 30-50° C. for 5-48 hours; the drying condition is drying at 60-150° C. for 6-24 hours.

[0021] Preferably, in step 4, the alkali source is one of sodium hydroxide, ammonia water and triethanolamine; and the Y source is one of yttrium nitrate, yttrium chloride and yttrium acetate.

[0022] Preferably, the drying condition in step 5 is drying at 80-150° C. for 12-24 hours.

[0023] Preferably, in step six, the mass ratio of the dry glue to deionized water is 0.1-3:1; the crystallization conditions are crystallization at 100-160°C for 6-72h; the washing conditions are washing with deionized water and ammonium nitrate solution at 40-60°C; the drying conditions are drying at 80-100°C for 6-12h; and the calcination conditions are calcination at 300-600°C for 5-24h.

[0024] The present invention also provides a method for directly converting a multi-level porous nano-capsule catalyst and an ethanol aqueous solution into butadiene. The conversion method comprises the following steps: granulating the catalyst prepared by the preparation method, loading it into a fixed bed reactor at normal pressure, introducing nitrogen for pretreatment, then pumping the ethanol aqueous solution into a vaporization chamber by a peristaltic pump for vaporization, and then mixing the vaporized ethanol with the nitrogen and entering the reactor for reaction to produce butadiene.

[0025] Preferably, the catalyst granulation is 20-40 mesh; the pretreatment temperature is 300-500°C; the pretreatment time is 2-12h; and the gas flow rate is 10-50mL·min-1.

[0026] Preferably, the vaporization temperature is 80-200°C, the ethanol and nitrogen composition is 1:1-6, the space velocity is 0.2-2.5h-1, and the reaction temperature is 300-500°C.

[0027] Compared with the prior art, the present invention has at least the following beneficial effects: the multi-level porous nano-capsule catalyst and its preparation method and the method for converting butadiene,

[0028] The multi-level porous nanocapsule catalyst uses ZnZr / Si-Beta as the core layer and Y / Si-Beta as the shell layer to construct a capsule structure catalyst. The catalyst provided by the present invention can directly convert 80% ethanol aqueous solution into butadiene, which is better than the traditional Si-Beta catalyst;

[0029] The preparation method provided by the present invention can not only shorten the synthesis cycle and avoid the use of hydrofluoric acid to pollute the environment, but also obtain a multi-level porous nanostructured molecular sieve. At the same time, the shell Y / Si-Beta in the catalyst provided by the present invention has strong water resistance and can inhibit the influence of water molecules on the active center. The shell Y / Si-Beta with strong water resistance can effectively strengthen the aldol condensation reaction, thereby improving the ethanol conversion rate and butadiene selectivity.

[0030] In addition, the method for directly converting ethanol aqueous solution to butadiene uses an already industrialized 80% ethanol aqueous solution as a raw material to directly convert butadiene. The Y species has a large ionic radius and is easy to interact with the silanol group to form a Lewis acid site with strong water resistance, so that the catalyst has strong water resistance. At the same time, the capsule structure can strengthen the aldol condensation reaction, thereby improving the catalytic activity and butadiene selectivity. This is a new method to inhibit the influence of water molecules on the active center of the catalyst. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] The drawings described herein are used to provide a further understanding of the present application and constitute a part of the present application. The illustrative embodiments of the present application and their descriptions are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings:

[0032] Figure 1 This is the XRD spectrum of the multi-level porous nanocapsule catalyst of the present invention;

[0033] Figure 2 This is a TEM photo of the multi-level porous nanocapsule catalyst of the present invention. DETAILED DESCRIPTION

[0034] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the drawings in the embodiments of the present invention, so that the implementation process of how the present application applies technical means to solve technical problems and achieve technical effects can be fully understood and implemented accordingly. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Example 1

[0035] (1) Dissolve zinc acetate and zirconium oxynitrate in deionized water at a Zn / Si molar ratio of 0.05 and a Zr / Si molar ratio of 0.3, stir for 0.5 h to form solution 1, and then add seed crystal Si-Beta to solution 1;

[0036] (2) The suspension was stirred for 1 hour, then evaporated and dried at 100°C for 12 hours, and calcined at 500°C for 6 hours to obtain a ZnZr / Si-Beta product;

[0037] (3) According to the molar ratio of tetraethylammonium hydroxide to tetraethylorthosilicate of 0.10, 5% tetraethylammonium hydroxide and 3% tetraethylorthosilicate were impregnated on the product obtained in step (2), ultrasonically treated at 40°C for 8h, and dried at 80°C for 12h to obtain a modified ZnZr / Si-Beta product;

[0038] (4) Add the remaining tetraethylammonium hydroxide and tetraethyl orthosilicate into deionized water, add sodium hydroxide at a molar ratio of sodium hydroxide to tetraethyl orthosilicate of 0.2, stir for 1 hour, then add yttrium nitrate at a Y / Si molar ratio of 0.5 and continue stirring for 2 hours;

[0039] (5) adding the product obtained in step (3) to step (4) and stirring continuously for 2 h, drying at 100° C. for 12 h, and grinding to obtain a dry glue;

[0040] (6) The dry glue obtained in step (5) was added into a polytetrafluoroethylene liner with a jacket at a mass ratio of m (dry glue): m (water) = 1:0.05, deionized water was added into the jacket, crystallized at 140° C. for 36 h, washed with deionized water at 50° C., dried at 100° C. for 12 h, and calcined at 550° C. for 6 h to obtain a hierarchical porous nano ZnZr / Si-Beta@Y / Si-Beta capsule catalyst.

[0041] (7) The catalyst product was pelletized into 20-40 mesh and loaded into a micro atmospheric fixed bed reactor to evaluate the catalytic performance. The catalyst was pretreated first, where the pretreatment conditions were: nitrogen, flow rate 30 mL min -1 , 350℃ for 5h, and the ethanol aqueous solution was pumped into the vaporization chamber by a peristaltic pump. The temperature of the vaporization chamber was maintained at 180℃, and then the vaporized ethanol was mixed with nitrogen and sent into the atmospheric pressure fixed bed reactor for catalytic performance evaluation. The reaction conditions were: ethanol aqueous solution / N2 =1:2, reaction temperature 350℃, space velocity WHSV=1.0h -1 The reaction products were analyzed online in a gas chromatograph (GC) equipped with a hydrogen flame ionization detector (FID) and a thermal conductivity detector (TCD). The results are shown in Table 1. Example 2

[0042] (1) Dissolve zinc nitrate and zirconium chloride in deionized water at a Zn / Si molar ratio of 0.05 and a Zr / Si molar ratio of 0.6, stir for 0.5 h to form solution 1, and then add seed crystal Si-Beta to solution 1;

[0043] (2) The suspension was stirred for 2 h, then evaporated and dried at 90 °C for 15 h, and calcined at 400 °C for 8 h to obtain a ZnZr / Si-Beta product;

[0044] (3) According to the molar ratio of tetrapropylammonium hydroxide to silica sol of 0.20, 8% tetrapropylammonium hydroxide and 6% silica sol were impregnated on the product obtained in step (2), ultrasonicated at 50°C for 12 hours, and dried at 100°C for 10 hours to obtain a modified ZnZr / Si-Beta product;

[0045] (4) adding the remaining tetrapropylammonium hydroxide and silica sol into deionized water, adding sodium hydroxide at a molar ratio of sodium hydroxide to silica sol of 0.3, stirring for 1 hour, and then adding yttrium nitrate at a Y / Si molar ratio of 0.8 and continuing stirring for 3 hours;

[0046] (5) adding the product obtained in step (3) to step (4) and stirring continuously for 2 h, drying at 80° C. for 24 h, and grinding to obtain dry glue;

[0047] (6) The dry glue obtained in step (5) was added into a polytetrafluoroethylene liner with a jacket at a mass ratio of m (dry glue): m (water) = 1:0.08, deionized water was added into the jacket, crystallized at 160° C. for 24 h, washed with deionized water at 40° C., dried at 80° C. for 12 h, and calcined at 600° C. for 12 h to obtain a hierarchical porous nano ZnZr / Si-Beta@Y / Si-Beta capsule catalyst.

[0048] (7) The performance test conditions were the same as those in Example 1. The results are shown in Table 1. Example 3

[0049] (1) Dissolve zinc nitrate and zirconium chloride in deionized water at a Zn / Si molar ratio of 0.06 and a Zr / Si molar ratio of 0.3, stir for 1 h to form solution 1, and then add seed crystal Si-Beta to solution 1;

[0050] (2) The suspension was stirred for 2 h, then evaporated and dried at 100 °C for 15 h, and calcined at 550 °C for 6 h to obtain a ZnZr / Si-Beta product;

[0051] (3) According to the molar ratio of tetrapropylammonium hydroxide to silica sol of 0.15, 6% tetrapropylammonium hydroxide and 2% silica sol were impregnated on the product obtained in step (2), ultrasonicated at 40°C for 6 hours, and dried at 80°C for 12 hours to obtain a modified ZnZr / Si-Beta product;

[0052] (4) adding the remaining tetrapropylammonium hydroxide and silica sol into deionized water, adding sodium hydroxide at a molar ratio of sodium hydroxide to silica sol of 0.3, stirring for 1 hour, and then adding yttrium nitrate at a Y / Si molar ratio of 1.0 and continuing stirring for 3 hours;

[0053] (5) adding the product obtained in step (3) to step (4) and continuously stirring for 2 h, drying at 100 °C for 24 h, and grinding to obtain a dry glue;

[0054] (6) The dry glue obtained in step (5) was added into a polytetrafluoroethylene liner with a jacket at a mass ratio of m (dry glue): m (water) = 1:0.10, deionized water was added into the jacket, crystallized at 140° C. for 36 h, washed with deionized water at 50° C., dried at 80° C. for 12 h, and calcined at 400° C. for 12 h to obtain a hierarchical porous nano ZnZr / Si-Beta@Y / Si-Beta capsule catalyst.

[0055] (7) The performance test conditions were the same as those in Example 1. The results are shown in Table 1. Example 4

[0056] (1) Dissolve zinc nitrate and zirconium chloride in deionized water at a Zn / Si molar ratio of 0.02 and a Zr / Si molar ratio of 0.4, stir for 0.5 h to form solution 1, and then add seed crystal Si-Beta to solution 1;

[0057] (2) The suspension was stirred for 2 h, then evaporated and dried at 80 °C for 20 h, and calcined at 300 °C for 10 h to obtain a ZnZr / Si-Beta product;

[0058] (3) According to the molar ratio of diethylamine to fumed silica of 0.20, 4% tetrapropylammonium hydroxide and 3% silica sol were impregnated on the product obtained in step (2), ultrasonicated at 50°C for 12 hours, and dried at 100°C for 24 hours to obtain a modified ZnZr / Si-Beta product;

[0059] (4) Add the remaining diethylamine and fumed silica to deionized water, add ammonia water at a molar ratio of ammonia water to fumed silica of 0.2, stir for 2 hours, then add yttrium chloride at a Y / Si molar ratio of 1.3 and continue stirring for 2 hours;

[0060] (5) Add the product obtained in step (3) to step (4) and continue stirring for 1 hour, dry at 80°C for 24 hours, and grind to obtain dry glue;

[0061] (6) The dry glue obtained in step (5) was added into a polytetrafluoroethylene liner with a jacket at a mass ratio of m (dry glue): m (water) = 1:0.20, deionized water was added into the jacket, crystallized at 160° C. for 6 h, washed with deionized water at 60° C., dried at 100° C. for 12 h, and calcined at 600° C. for 5 h to obtain a hierarchical porous nano ZnZr / Si-Beta@Y / Si-Beta capsule catalyst.

[0062] (7) The performance test conditions were the same as those in Example 1. The results are shown in Table 1. Example 5

[0063] (1) Dissolve zinc nitrate and zirconium chloride in deionized water at a Zn / Si molar ratio of 0.06 and a Zr / Si molar ratio of 0.3, stir for 1 h to form solution 1, and then add seed crystal Si-Beta to solution 1;

[0064] (2) The suspension was stirred for 4 hours, then evaporated and dried at 100°C for 15 hours, and calcined at 350°C for 8 hours to obtain a ZnZr / Si-Beta product;

[0065] (3) According to the molar ratio of tetrapropylammonium hydroxide to fumed silica being 0.25, 10% tetrapropylammonium hydroxide and 6% silica sol were respectively impregnated on the product obtained in step (2), ultrasonicated at 30°C for 36 hours, and dried at 150°C for 5 hours to obtain a modified ZnZr / Si-Beta product;

[0066] (4) Add the remaining tetraethylammonium hydroxide and fumed silica to deionized water, add sodium hydroxide at a molar ratio of sodium hydroxide to fumed silica of 0.3, stir for 2 hours, then add yttrium acetate at a Y / Si molar ratio of 1.5 and continue stirring for 1 hour;

[0067] (5) adding the product obtained in step (3) to step (4) and stirring continuously for 2 h, drying at 80° C. for 24 h, and grinding to obtain dry glue;

[0068] (6) The dry glue obtained in step (5) was added into a polytetrafluoroethylene liner with a jacket at a mass ratio of m (dry glue): m (water) = 1:0.01, deionized water was added into the jacket, crystallized at 100° C. for 72 h, washed with deionized water at 40° C., dried at 80° C. for 12 h, and calcined at 300° C. for 24 h to obtain a hierarchical porous nano ZnZr / Si-Beta@Y / Si-Beta capsule catalyst.

[0069] (7) The performance test conditions were the same as those in Example 1. The results are shown in Table 1. Example 6

[0070] (1) Dissolve zinc nitrate and zirconium chloride in deionized water at a Zn / Si molar ratio of 0.06 and a Zr / Si molar ratio of 0.3, stir for 1 h to form solution 1, and then add seed crystal Si-Beta to solution 1;

[0071] (2) The suspension was stirred for 4 hours, then evaporated and dried at 120°C for 12 hours, and calcined at 550°C for 4 hours to obtain a ZnZr / Si-Beta product;

[0072] (3) According to the molar ratio of tetrapropylammonium bromide to tetraethyl orthosilicate of 0.05, 2% tetrapropylammonium hydroxide and 1% silica sol were impregnated on the product obtained in step (2), ultrasonicated at 50°C for 24 hours, and dried at 100°C for 12 hours to obtain a modified ZnZr / Si-Beta product;

[0073] (4) Add the remaining tetrapropylammonium bromide and tetraethyl orthosilicate to deionized water, add triethanolamine at a molar ratio of triethanolamine to tetraethyl orthosilicate of 0.2, stir for 1 hour, then add yttrium acetate at a Y / Si molar ratio of 1.0 and continue stirring for 2 hours;

[0074] (5) adding the product obtained in step (3) to step (4) and continuously stirring for 3 h, drying at 150° C. for 12 h, and grinding to obtain a dry glue;

[0075] (6) The dry glue obtained in step (5) was added into a polytetrafluoroethylene liner with a jacket at a mass ratio of m (dry glue): m (water) = 1:0.50, deionized water was added into the jacket, crystallized at 140° C. for 48 h, washed with deionized water at 50° C., dried at 90° C. for 10 h, and calcined at 550° C. for 10 h to obtain a hierarchical porous nano ZnZr / Si-Beta@Y / Si-Beta capsule catalyst.

[0076] (7) The performance test conditions were the same as those in Example 1. The results are shown in Table 1.

[0077] Table 1 Performance test product comparison table

[0078]

[0079] Comparative Example 1

[0080] The ZnZr / Si-Beta catalyst prepared in Example 1 was reacted under the same test conditions as in Example 1. The catalytic performance is shown in Table 2.

[0081] Comparative Example 2

[0082] In step (5) of Example 1, no ZnZr / Si-Beta catalyst was added to obtain a Y / Si-Beta catalyst. The reaction was carried out under the same test conditions as in Example 1. The catalytic performance is shown in Table 2.

[0083] Comparative Example 3

[0084] The catalysts in Comparative Examples 1 and 2 were loaded in separate beds and reacted under the same test conditions as in Example 1. The catalytic performance is shown in Table 2.

[0085] Comparative Example 4

[0086] The catalysts in Comparative Example 1 and Comparative Example 2 were physically mixed and reacted under the same test conditions as Example 1. The catalytic performance is shown in Table 2.

[0087] Table 2 Performance test product comparison table

[0088]

[0089] Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative work shall fall within the scope of protection of the present invention; although the present invention has been described in detail with reference to the aforementioned embodiments, for technicians in this field, they can still modify the technical solutions recorded in the aforementioned embodiments, or make equivalent substitutions for some of the technical features therein, and any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention shall be included in the scope of protection of the present invention.

Claims

1. A method for preparing a multi-level porous nanocapsule catalyst, characterized in that: The catalyst comprises a core layer and a shell layer, the core layer is ZnZr / Si-Beta, the shell layer is Y / Si-Beta, and the preparation method of the catalyst comprises the following steps: Step 1: dissolve the Zn source and the Zr source in deionized water in proportion, stir for 0.1-1h to form a solution 1, and then add the seed crystal Si-Beta to the solution 1 to form a mixed suspension; Step 2: Stir the mixed suspension for 0.5-5 hours, evaporate and dry, and calcine to obtain a ZnZr / Si-Beta product; Step 3: According to the molar ratio of template to Si source of 0.05-0.25, a certain amount of template and silicon source are respectively impregnated on the product obtained in step 2, and ultrasonic and dried to obtain a ZnZr / Si-Beta product modified with template and silicon source; Step 4: Add the remaining template and Si source into deionized water, add alkali source at a molar ratio of alkali source to Si source of 0.1-0.3, stir for 0.5-2h, then add Y source at a Y / Si molar ratio of 0.5-1.5 and continue stirring for 1-4h; Step 5: Add the product obtained in step 3 to step 4 and continue stirring for 1-3 hours, drying and grinding to obtain dry glue; Step 6: Add the dry glue obtained in step 5 to a polytetrafluoroethylene liner with a jacket, add deionized water in a certain mass ratio to the jacket, perform crystallization, washing, drying, and calcination to obtain a multi-level porous nano ZnZr / Si-Beta@Y / Si-Beta capsule catalyst.

2. The method for preparing a multi-level porous nanocapsule catalyst according to claim 1, characterized in that: In the step 1, the Zn source is selected from one of zinc acetate, zinc nitrate and zinc chloride; the Zr source is selected from one of zirconium oxynitrate, zirconium n-propoxide, zirconium chloride and zirconium sulfate; The molar ratio of the Zn source to the Zr source is 0.01-0.1 for Zn / Si and 0.1-0.6 for Zr / Si.

3. The method for preparing a multi-level porous nanocapsule catalyst according to claim 1, characterized in that: The evaporation drying condition of the step 2 is drying at 80-120° C. for 12-24 hours; the roasting condition is roasting at 300-550° C. for 4-10 hours.

4. The method for preparing a multi-level porous nanocapsule catalyst according to claim 1, characterized in that: In the step 3, the template agent is one of tetrapropylammonium hydroxide, tetrapropylammonium bromide, tetraethylammonium hydroxide and diethylamine; the silicon source is one of tetraethyl orthosilicate, fumed silica and silica sol; The certain amount of the template agent refers to a loading amount of the template agent of 2%-10%, and a loading amount of the Si source of 1%-6%; The ultrasonic condition in the step 3 is ultrasonication at 30-50° C. for 5-48 hours; the drying condition is drying at 60-150° C. for 6-24 hours.

5. The method for preparing a multi-level porous nanocapsule catalyst according to claim 1, characterized in that: In the step 4, the alkali source is one of sodium hydroxide, ammonia water and triethanolamine; and the Y source is one of yttrium nitrate, yttrium chloride and yttrium acetate.

6. The method for preparing a multi-level porous nanocapsule catalyst according to claim 1, characterized in that: The drying condition in step 5 is drying at 80-150° C. for 12-24 hours.

7. The method for preparing a multi-level porous nanocapsule catalyst according to claim 1, characterized in that: In the step six, the mass ratio of the dry glue to the deionized water is 0.1-3:1; the crystallization conditions are crystallization at 100-160°C for 6-72 hours; the washing conditions are washing with deionized water and ammonium nitrate solution at 40-60°C; the drying conditions are drying at 80-100°C for 6-12 hours; and the calcination conditions are calcination at 300-600°C for 5-24 hours.

8. A method for converting ethanol into butadiene using the catalyst prepared by the method for preparing the multi-level porous nanocapsule catalyst according to any one of claims 1 to 7, characterized in that: The conversion method comprises the following steps: granulating the catalyst prepared by the preparation method according to any one of claims 1 to 7, loading it into a fixed bed reactor at normal pressure, introducing nitrogen for pretreatment, then pumping the ethanol aqueous solution into a vaporization chamber by a peristaltic pump for vaporization, and then mixing the vaporized ethanol with nitrogen and entering the reactor for reaction to produce butadiene.

9. A method for converting ethanol into butadiene using the catalyst prepared by the method for preparing a multi-level porous nanocapsule catalyst according to claim 8, characterized in that: The catalyst granulation is 20-40 mesh; the pretreatment temperature is 300-500°C; the pretreatment time is 2-12h; the gas flow rate is 10-50mL·min -1 .

10. A method for converting ethanol into butadiene using the catalyst prepared by the method for preparing a multi-level porous nanocapsule catalyst according to claim 8, characterized in that: The vaporization temperature is 80-200°C, the composition of ethanol and nitrogen is 1:1-6, and the air velocity is 0.2-2.5h -1 , the reaction temperature is 300-500℃.

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