Cu-MEL zeolite confinement catalyst as well as preparation method and application thereof

Abstract

The invention provides a Cu-MEL zeolite confinement catalyst as well as a preparation method and application thereof, and belongs to the technical field of catalytic materials. According to the Cu-MEL zeolite confinement catalyst disclosed by the invention, Cu nanoparticles are confined in pores of MEL zeolite and are loaded on the surface of the MEL zeolite. The method has the advantages that according to a confinement structure, Cu nano particles are packaged in MEL zeolite pore channels, and Cu particle aggregation is inhibited through the space confinement effect of a zeolite framework; organic-inorganic synergism: zeolite pore channels contain [Cu (NH3) 4] < 2 + > or [Cu (en)] < 2 + > complex ions, so that dispersity and stability are enhanced; and surface passivation: selectively passivating Cu sites on the outer surface of the zeolite to improve the selectivity. The zeolite confinement strategy is combined with the copper-based catalyst for the first time, Cu nano particles are limited through MEL pore channels, and the industrial problem that the copper-based catalyst is prone to inactivation at high temperature is solved by combining the surface passivation technology.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of catalytic materials, and particularly relates to a Cu-MEL zeolite confined catalyst and a preparation method and application thereof. BACKGROUND

[0002] Ethanol dehydrogenation to acetaldehyde is an important industrial reaction, but the existing copper-based catalysts have problems of easy sintering at high temperature, low selectivity and short service life. For example, the Cu / C catalyst in the related art has a high conversion rate (75%) at 260 DEG C, but the service life is only 40 h, and the problems of simultaneous consideration of activity and long service life cannot be solved. SUMMARY

[0003] Therefore, the present application aims to provide a Cu-MEL zeolite confined catalyst and a preparation method and application thereof. The Cu-MEL zeolite confined catalyst provided by the present application has high activity and long service life, and has important industrial value.

[0004] In order to achieve the above-mentioned application purposes, the present application provides the following technical solutions:

[0005] The present application provides a Cu-MEL zeolite confined catalyst, which comprises Cu nanoparticles and MEL zeolite, and the Cu nanoparticles are confined in the pores of the MEL zeolite and loaded on the surface of the MEL zeolite.

[0006] Preferably, the loading amount of the Cu nanoparticles in the Cu-MEL zeolite confined catalyst is 1-15 wt%.

[0007] Preferably, the particle size of the Cu nanoparticles is 0.5-5.0 nm.

[0008] The present application also provides a preparation method of the Cu-MEL zeolite confined catalyst according to the above-mentioned technical solutions, which comprises the following steps:

[0009] The Cu-MEL precursor is obtained by mixing a Cu salt, an alkaline substance, a silicon source, a template agent and a solvent and then performing a hydrothermal sol-gel reaction;

[0010] The Cu-MEL precursor is calcined in a N2 / H2 mixed atmosphere to obtain a Cu-based catalyst;

[0011] The Cu-MEL precursor is passivated by using an amine compound solution to obtain the Cu-MEL zeolite confined catalyst.

[0012] Preferably, the alkaline substance comprises ammonia and / or ethylenediamine.

[0013] Preferably, the molar ratio of the Cu salt to the alkaline substance is 1:4-10.

[0014] Preferably, the temperature of the calcination is 400-600℃, and the time is 3-6h.

[0015] Preferably, the amine compound in the amine compound solution comprises aniline and / or alkyl aniline.

[0016] Preferably, the molar ratio of the amine compound in the amine compound solution to the Cu salt is 1-5:1.

[0017] The application also provides application of the Cu-MEL zeolite confined catalyst or the Cu-MEL zeolite confined catalyst prepared by the preparation method in the preparation of acetaldehyde from ethanol by catalytic dehydrogenation.

[0018] The application provides a Cu-MEL zeolite confined catalyst, which comprises Cu nanoparticles and MEL zeolite, wherein the Cu nanoparticles are confined in the pores of the MEL zeolite and are loaded on the surface of the MEL zeolite.

[0019] Compared with the prior art, the application has the following beneficial effects:

[0020] Confined structure: the Cu nanoparticles are encapsulated in the pores of the MEL zeolite, and the spatial confinement effect of the zeolite framework is utilized to inhibit the agglomeration of Cu particles;

[0021] Organic-inorganic synergy: the Cu-MEL precursor contains [Cu(NH3)4] 2+ or [Cu(en)] 2+ complex ions, which enhances the dispersity and stability;

[0022] Surface passivation: selective passivation of Cu sites on the outer surface of the zeolite improves the selectivity.

[0023] The application also provides a preparation method of the Cu-MEL zeolite confined catalyst, in order to confine the metal species in the non-framework position of the molecular sieve in situ, two key factors need to be considered: (1) the mismatch between the rapid formation of the metal and the crystallization of the zeolite usually leads to the separation of the metal and the zeolite crystal, therefore, the formation rate of the metal and the zeolite should be balanced; (2) the interaction between the template, the starting material and the metal precursor can promote the in-situ confinement of the metal species in the zeolite matrix. In the application, ammonia or ethylenediamine as an amine stabilizer can not only be used for stabilizing the metal cation, but also can promote the interaction between the metal complex and the initial silicate crystal nucleus in the self-assembly process of the zeolite framework. In the synthesis process, the SiO2 network sol structure can be rearranged in structure with the help of the template cation, and the ammonia or ethylenediamine as the ligand of the complex Cu cation plays a role through the double mechanisms of "structure guiding" and "charge repulsion". The structure guiding: the template cation is combined with the silicon dioxide tetrahedron through the electrostatic interaction, guides the formation of the ten-membered ring channel, and the steric hindrance of the quaternary ammonium salt head group limits the generation of other channel structures; the charge repulsion: the Cu ion increases the radius after being complexed with the amine, and the mutual repulsion force is generated through the positive charge, so that the Cu nanoparticles are formed in a high dispersion distribution on the carrier.

[0024] The application first combines the zeolite confinement strategy with the copper-based catalyst, limits the migration of the Cu species through the MEL channel, and solves the industry problem that the copper-based catalyst is easy to be deactivated at high temperature by combining the surface passivation technology, so as to provide an efficient and long-life solution for the ethanol dehydrogenation. The data of the embodiments show that the Cu-MEL zeolite confined catalyst of the application has the ethanol conversion rate ≥ 30%, the acetaldehyde selectivity ≥ 95% under the conditions that the temperature is 200-250℃, the ethanol mass space velocity is 0.5-5h-1, and the continuous operation time is 500h. -1 BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 The XRD diffraction patterns of the catalysts prepared for Examples 1-4 and Comparative Example 1. DETAILED DESCRIPTION

[0026] The application provides a Cu-MEL zeolite confined catalyst, which comprises Cu nanoparticles and MEL zeolite, and the Cu nanoparticles are confined in the channel of the MEL zeolite and loaded on the surface of the MEL zeolite.

[0027] ​In the present application, the loading amount of Cu nanoparticles in the Cu-MEL zeolite confined catalyst is preferably 1-15wt%, and can be specifically 1wt%, 1.6wt%, 2.2wt%, 2.8wt%, 3.1wt%, 4.7wt%, 5wt%, 10.3wt%, 11wt%, 12wt%, 13wt%, 14wt% or 15wt%.

[0028] In the present application, the particle size of the Cu nanoparticles is preferably 0.5-5.0nm, and can be specifically 0.5, 1.0, 1.5, 2, 3, 4 or 5nm.

[0029] In the present application, the Cu-MEL zeolite confined catalyst is a high dispersion copper-based catalyst based on zeolite confinement, and the Cu nanoparticles are confined in the pores of the MEL zeolite and loaded on the surface of the MEL zeolite, forming a high dispersion form.

[0030] The present application also provides a preparation method of the Cu-MEL zeolite confined catalyst described in the above technical solution, comprising the following steps:

[0031] The Cu-MEL precursor is obtained by mixing the Cu salt, the alkaline substance, the silicon source, the template agent and the solvent and then performing a hydrothermal sol-gel reaction.

[0032] The Cu-MEL precursor is calcined in a N2 / H2 mixed atmosphere to obtain the Cu-based catalyst.

[0033] The Cu-MEL precursor is passivated by using an amine compound solution to obtain the Cu-MEL zeolite confined catalyst.

[0034] In the present application, the raw materials used are commercially available products in the art unless otherwise specified.

[0035] In the present application, the Cu-MEL precursor is obtained by mixing the Cu salt, the alkaline substance, the silicon source, the template agent and the solvent and then performing a hydrothermal sol-gel reaction.

[0036] In the present application, the molar ratio of the Cu salt to the alkaline substance is preferably 1:4-10, and can be specifically 1:4, 1:5, 1:6, 1:7, 1:8, 1:9 or 1:10.

[0037] In the present application, the alkaline substance preferably includes ammonia and / or ethylenediamine.

[0038] In the present application, the concentration of the ammonia is preferably 25-28wt%.

[0039] In the present application, the silicon source preferably comprises one or more of a silica sol solution, tetraethyl silicate and tetramethyl silicate, and the silica sol solution preferably has a solid content of 20-40 wt%, and can be 20 wt%, 30 wt% or 40 wt% in particular.

[0040] In the present application, the template agent is preferably tetrapropyl ammonium hydroxide (TPAOH) and / or cetyltrimethylammonium bromide (CTAB).

[0041] In the present application, the template agent is preferably used in an amount of 1-5% of the amount of substance of the Cu salt, and can be 1%, 2%, 3%, 4% or 5% in particular.

[0042] In the present application, the solvent is preferably methanol or ethanol, and the mass ratio of the solvent to the silicon source is preferably 2-5:1, and can be 2:1, 3:1, 4:1 or 5:1 in particular.

[0043] In the present application, the temperature of the hydrothermal sol-gel reaction is preferably 80-120℃, and can be 80℃, 90℃, 100℃, 110℃ or 120℃ in particular, and the time is preferably 5-10h, and can be 5h, 6h, 7h, 8h, 9h or 10h in particular.

[0044] In the present application, the hydrothermal sol-gel reaction is preferably carried out in a hydrothermal kettle, and the [Cu(NH3)4] 2+ or [Cu(en)] 2+ complex ions are constructed in the zeolite pores through the hydrothermal sol-gel reaction, to enhance dispersibility and stability.

[0045] In the present application, the Cu salt, template agent, basic substance and solvent are preferably mixed and stirred to dissolve uniformly, the silicon source is added under stirring and stirred thoroughly, and then the hydrothermal sol-gel reaction is carried out.

[0046] After obtaining the Cu-MEL precursor, the Cu-MEL precursor is calcined in a N2 / H2 mixed atmosphere to obtain a Cu-based catalyst.

[0047] In the present application, the volume percentage of hydrogen in the N2 / H2 mixed atmosphere is preferably 5-10%, and can be 5%, 6%, 7%, 8%, 9% or 10% in particular.

[0048] In the present application, the temperature of the calcination is preferably 400-600℃, and can be 400℃, 450℃, 500℃, 550℃ or 600℃ in particular, and the time is preferably 3-6h, and can be 3h, 4h, 5h or 6h in particular, and the calcination dissociates active metal Cu nanoparticle clusters into highly dispersed active sites.

[0049] After obtaining the Cu-based catalyst, the Cu-MEL precursor is passivated by an amine compound solution to obtain the Cu-MEL zeolite confined catalyst.

[0050] In the present application, the amine compound in the amine compound solution preferably includes aniline and / or alkyl aniline, and the alkyl aniline preferably includes one or more of N-methyl aniline, N-ethyl aniline and N-butyl aniline.

[0051] In the present application, the solvent of the amine compound solution preferably includes an alcohol solvent, and the alcohol solvent is more preferably ethanol.

[0052] In the present application, the concentration of the amine compound solution is preferably 1.0 wt%.

[0053] In the present application, the molar ratio of the amine compound in the amine compound solution to the Cu salt is preferably 1-5:1, and can be specifically 1:1, 2:1, 3:1, 4:1 or 5:1.

[0054] In the present application, the temperature of the passivation is preferably 60-80℃, and can be specifically 60℃, 70℃ or 80℃, and the time is preferably 3-6h, and can be specifically 3h, 4h, 5h or 6h. The passivation passivates the Cu exposed on the surface by the amine compound, while retaining the active sites in the pores, thereby improving the stability and selectivity of the catalyst.

[0055] After the passivation is completed, the Cu-MEL zeolite confined catalyst is preferably obtained by air drying.

[0056] The present application also provides the application of the Cu-MEL zeolite confined catalyst described in the above technical solution or the Cu-MEL zeolite confined catalyst prepared by the preparation method described in the above technical solution in the preparation of acetaldehyde by catalytic dehydrogenation of ethanol.

[0057] In the present application, the conditions of the reaction preferably include: fixed bed continuous reaction, temperature 200-250℃ (which can be specifically 200℃, 210℃, 220℃, 230℃, 240℃ or 250℃), ethanol mass space velocity 0.5-5h -1 (which can be specifically 0.5h, 1h, 2h, 3h, 4h or 5h -1 ).

[0058] The technical solutions in the present application will be described clearly and completely in combination with the embodiments in the present application. Obviously, the described embodiments are only some of the embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all the other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0059] Example 1

[0060] Preparation of Cat-1

[0061] 1. Weigh 1 mmol of copper nitrate, 4 mmol of ethylenediamine and 0.01 mmol of TPAOH into 64 g of methanol and stir to dissolve;

[0062] 2. Weigh 31.7 g of 20 wt% silica sol into the above solution and stir to uniform;

[0063] 3. Put the above mixture into a hydrothermal kettle and seal, keep at 80 °C for 10 h, and then cool naturally;

[0064] 4. Put the obtained gel solid after cooling into N2 / H2 mixed atmosphere (5% of hydrogen by volume) and calcine at 400 °C for 6 h to obtain a Cu-based catalyst;

[0065] 5. Dissolve 1 mmol of aniline in 9.2 g of ethanol, immerse the Cu-based catalyst into the aniline ethanol solution and keep at 60 °C for 3 h, and then dry to obtain Cat-1.

[0066] Example 2

[0067] Preparation of Cat-2

[0068] 1. Weigh 1 mmol of copper nitrate, 4 mmol of ethylenediamine and 0.03 mmol of TPAOH into 13 g of methanol and stir to dissolve;

[0069] 2. Weigh 6.5 g of 20 wt% silica sol into the above solution and stir to uniform;

[0070] 3. Put the above mixture into a hydrothermal kettle and seal, keep at 80 °C for 10 h, and then cool naturally;

[0071] 4. Put the obtained gel solid after cooling into N2 / H2 mixed atmosphere (5% of hydrogen by volume) and calcine at 400 °C for 6 h to obtain a Cu-based catalyst;

[0072] 5. Dissolve 1 mmol of aniline in 9.2 g of ethanol, immerse the Cu-based catalyst into the aniline ethanol solution and keep at 60 °C for 3 h, and then dry to obtain Cat-2.

[0073] Example 3

[0074] Preparation of Cat-3

[0075] 1. Weigh 1 mmol of copper nitrate, 4 mmol of ethylenediamine and 0.05 mmol of TPAOH into 9.1 g of methanol and stir to dissolve;

[0076] 2. 1.82 g of 20 wt% silica sol was weighed into the above solution and stirred to homogeneity;

[0077] 3. The above mixture was sealed in an autoclave and kept at 80 °C for 10 h, and then cooled naturally;

[0078] 4. The obtained gel solid after cooling was placed in a N2 / H2 mixed atmosphere (5% hydrogen by volume) and calcined at 400 °C for 6 h to obtain the Cu-based catalyst;

[0079] 5. 1 mmol of aniline was dissolved in 9.2 g of ethanol, the Cu-based catalyst was immersed in the aniline ethanol solution and kept at 60 °C for 3 h, and then dried to obtain Cat-3.

[0080] Example 4

[0081] Preparation of Cat-4

[0082] 1. 1 mmol of copper nitrate, 10 mmol of ethylenediamine, and 0.05 mmol of CTAB were dissolved in 20 g of ethanol by stirring;

[0083] 2. 10 g of tetraethyl orthosilicate was weighed into the above solution and stirred to homogeneity;

[0084] 3. The above mixture was sealed in an autoclave and kept at 120 °C for 5 h, and then cooled naturally;

[0085] 4. The obtained gel solid after cooling was placed in a N2 / H2 mixed atmosphere (5% hydrogen by volume) and calcined at 600 °C for 3 h to obtain the Cu-based catalyst;

[0086] 5. 5 mmol of aniline was dissolved in 46 g of ethanol, the Cu-based catalyst was immersed in the aniline ethanol solution and kept at 80 °C for 6 h, and then dried to obtain Cat-4.

[0087] Example 5

[0088] Preparation of Cat-5

[0089] 1. 1 mmol of copper nitrate, 10 mmol of ethylenediamine, and 0.05 mmol of CTAB were dissolved in 20 g of ethanol by stirring;

[0090] 2. 10 g of tetraethyl orthosilicate was weighed into the above solution and stirred to homogeneity;

[0091] 3. The above mixture was sealed in an autoclave and kept at 120 °C for 5 h, and then cooled naturally;

[0092] 4. The obtained gel solid after cooling was placed in N2 / H2 mixed atmosphere (wherein the volume percentage of hydrogen is 5%), and calcined at 600°C for 3h to obtain the Cu-based catalyst;

[0093] 5. 5mmol of N-methylaniline was dissolved in 46g of ethanol, the Cu-based catalyst was immersed in the ethanol solution of N-methylaniline, and kept at 80°C for 6h, and then dried to obtain Cat-5.

[0094] Example 6

[0095] Preparation of Cat-6

[0096] 1. 1mmol of copper nitrate, 0.35g of concentrated ammonia water (concentration 28wt%), and 0.03mmol of CTAB were dissolved in 20g of methanol by stirring;

[0097] 2. 10g of tetramethyl silicate was weighed and added to the above solution and stirred uniformly;

[0098] 3. The above mixture was sealed in an autoclave and kept at 100°C for 8h, and then naturally cooled;

[0099] 4. The obtained gel solid after cooling was placed in N2 / H2 mixed atmosphere (wherein the volume percentage of hydrogen is 5%), and calcined at 500°C for 5h to obtain the Cu-based catalyst;

[0100] 5. 3mmol of aniline was dissolved in 27.6g of ethanol, the Cu-based catalyst was immersed in the ethanol solution of aniline, and kept at 70°C for 6h, and then dried to obtain Cat-6.

[0101] Example 7

[0102] Preparation of Cat-7

[0103] 1. 1mmol of copper nitrate, 0.50g of concentrated ammonia water (concentration 28wt%), and 0.03mmol of CTAB were dissolved in 20g of methanol by stirring;

[0104] 2. 8g of tetraethyl silicate was weighed and added to the above solution and stirred uniformly;

[0105] 3. The above mixture was sealed in an autoclave and kept at 100°C for 8h, and then naturally cooled;

[0106] 4. The obtained gel solid after cooling was placed in N2 / H2 mixed atmosphere (wherein the volume percentage of hydrogen is 5%), and calcined at 500°C for 5h to obtain the Cu-based catalyst;

[0107] 5. 3 mmol of aniline was dissolved in 27.6 g of ethanol, the Cu-based catalyst was immersed in the aniline ethanol solution at 70 °C for 6 h, and then dried to obtain Cat-7.

[0108] Example 8

[0109] Preparation of Cat-8

[0110] 1. 1 mmol of copper nitrate, 0.68 g of concentrated ammonia water (concentration 28 wt%), and 0.03 mmol of CTAB were dissolved in 10 g of ethanol by stirring;

[0111] 2. 2 g of tetraethyl silicate was added to the above solution and stirred uniformly;

[0112] 3. The above mixture was sealed in an autoclave and kept at 100 °C for 8 h, and then naturally cooled;

[0113] 4. The obtained gel solid after cooling was placed in a N2 / H2 mixed gas atmosphere (5% hydrogen by volume), and calcined at 500 °C for 5 h to obtain a Cu-based catalyst;

[0114] 5. 3 mmol of aniline was dissolved in 27.6 g of ethanol, the Cu-based catalyst was immersed in the aniline ethanol solution at 70 °C for 6 h, and then dried to obtain Cat-8.

[0115] Example 9

[0116] Preparation of Cat-9

[0117] 1. 1 mmol of copper nitrate, 0.68 g of concentrated ammonia water (concentration 28 wt%), and 0.03 mmol of CTAB were dissolved in 30 g of ethanol by stirring;

[0118] 2. 10 g of 40 wt% silica sol was added to the above solution and stirred uniformly;

[0119] 3. The above mixture was sealed in an autoclave and kept at 100 °C for 8 h, and then naturally cooled;

[0120] 4. The obtained gel solid after cooling was placed in a N2 / H2 mixed gas atmosphere (5% hydrogen by volume), and calcined at 500 °C for 5 h to obtain a Cu-based catalyst;

[0121] 5. 3 mmol of aniline was dissolved in 27.6 g of ethanol, the Cu-based catalyst was immersed in the aniline ethanol solution at 70 °C for 6 h, and then dried to obtain Cat-9.

[0122] Example 10

[0123] Preparation of Cat-10

[0124] 1. Weigh 1 mmol of copper nitrate, 0.68 g of concentrated ammonia water (concentration 28 wt%), and 0.03 mmol of CTAB into 30 g of ethanol and stir to dissolve;

[0125] 2. Weigh 10 g of 40 wt% silica sol into the above solution and stir to uniform;

[0126] 3. Put the above mixture into a hydrothermal kettle and seal, keep at 100°C for 8 h, and then cool naturally;

[0127] 4. Put the obtained gel solid after cooling into a N2 / H2 mixed atmosphere (5% hydrogen by volume), and calcine at 500°C for 5 h to obtain a Cu-based catalyst;

[0128] 5. Dissolve 3 mmol of N-ethyl aniline in 27.6 g of ethanol, immerse the Cu-based catalyst in the N-ethyl aniline ethanol solution, keep at 70°C for 6 h, and then dry to obtain Cat-10.

[0129] Example 11

[0130] Preparation of Cat-11

[0131] 1. Weigh 1 mmol of copper nitrate, 5 mmol of ethylenediamine, and 0.03 mmol of CTAB into 25 g of ethanol and stir to dissolve;

[0132] 2. Weigh 5 g of 40 wt% silica sol into the above solution and stir to uniform;

[0133] 3. Put the above mixture into a hydrothermal kettle and seal, keep at 100°C for 8 h, and then cool naturally;

[0134] 4. Put the obtained gel solid after cooling into a N2 / H2 mixed atmosphere (5% hydrogen by volume), and calcine at 500°C for 5 h to obtain a Cu-based catalyst;

[0135] 5. Dissolve 3 mmol of aniline in 27.6 g of ethanol, immerse the Cu-based catalyst in the aniline ethanol solution, keep at 70°C for 6 h, and then dry to obtain Cat-11.

[0136] Example 12

[0137] Preparation of Cat-12

[0138] 1. Weigh 1 mmol of copper nitrate, 5 mmol of ethylenediamine, and 0.03 mmol of CTAB into 25 g of ethanol and stir to dissolve;

[0139] 2. 5g of 40wt% silica sol was weighed and added into the above solution and stirred uniformly;

[0140] 3. The above mixture was sealed in an autoclave and kept at 100°C for 8h, and then naturally cooled;

[0141] 4. The obtained gel solid after cooling was placed in a N2 / H2 mixed atmosphere (5% of hydrogen by volume) and calcined at 500°C for 5h to obtain a Cu-based catalyst;

[0142] 5. 3mmol of N-butylaniline was dissolved in 27.6g of ethanol, the Cu-based catalyst was immersed in the N-butylaniline ethanol solution and kept at 70°C for 6h, and then dried to obtain Cat-12.

[0143] Comparative Example 1

[0144] Preparation of Cat-13

[0145] 1. 1mmol of copper nitrate was weighed and dissolved in 25g of ethanol and stirred to dissolve;

[0146] 2. 2g of SiO2 carrier was weighed and immersed in the above solution for 10h;

[0147] 3. The catalyst precursor was obtained by filtration;

[0148] 4. The precursor was placed in a N2 / H2 mixed atmosphere (5% of hydrogen by volume) and calcined at 500°C for 5h to obtain Cat-13.

[0149] Comparative Example 2

[0150] Preparation of Cat-14

[0151] The same as Example 1, except that surface passivation was not performed, to obtain Cat-14.

[0152] Figure 1 The XRD diffraction patterns of the catalysts prepared in Examples 1-4 and Comparative Example 1 showed that no characteristic diffraction peak of Cu was found in the catalysts of Examples 1-4, and the Cu / SiO2 catalyst prepared by Cat-13 impregnation method showed a clear CuO characteristic peak, indicating that CuO in the Cu-MEL zeolite confined catalyst existed in the form of high dispersion in the carrier.

[0153] Catalytic performance test

[0154] Test conditions: fixed bed reactor, catalyst loading 1.0g, reaction temperature 200-250°C, pressure normal pressure, ethanol mass space velocity 0.5-5h -1The reaction liquid was determined by Agilent 8860 gas chromatograph FID detector and the tail gas was analyzed and determined by Shimadzu 2014C TCD detector when the reaction was 100 h.

[0155] Table 1 is the Cu loadings and catalytic effect test data of the examples and comparative examples, and it can be seen that the catalysts of the present application can achieve high conversion of ethanol and high selectivity of acetaldehyde (>95%) at a lower temperature (200-210℃) and Cu loading, and the catalysts can be stably operated for more than 100 h, and have significant application value.

[0156] Table 1 is the Cu loadings and catalytic effect test data of the examples and comparative examples, and it can be seen that the catalysts of the present application can achieve high conversion of ethanol and high selectivity of acetaldehyde (>95%) at a lower temperature (200-210℃) and Cu loading, and the catalysts can be stably operated for more than 100 h, and have significant application value.

[0157]

[0158] The above only describes the preferred embodiments of the present application, and does not limit the present application in any form. It should be noted that for ordinary skilled persons in the art, several improvements and refinements can be made without departing from the principles of the present application, and these improvements and refinements should also be considered as the protection scope of the present application.

Claims

1. A Cu-MEL zeolite confined catalyst characterized in that, The Cu-MEL zeolite confined catalyst comprises Cu nanoparticles and MEL zeolite, the Cu nanoparticles being confined in the channels of the MEL zeolite and supported on the surface of the MEL zeolite.

2. The Cu-MEL zeolite confined catalyst according to claim 1, characterized in that, The loading amount of the Cu nanoparticles in the Cu-MEL zeolite confined catalyst is 1-15 wt%.

3. The Cu-MEL zeolite confined catalyst of claim 1, wherein, The particle size of the Cu nanoparticles is 0.5-5.0 nm.

4. Process for the preparation of a Cu-MEL zeolite confined catalyst according to any one of claims 1 to 3, characterized in that, The method comprises the following steps: mixing a Cu salt, a basic substance, a silicon source, a template agent and a solvent to perform a hydrothermal sol-gel reaction, thereby obtaining a Cu-MEL precursor; firing the Cu-MEL precursor in a N2 / H2 mixed atmosphere, thereby obtaining a Cu-based catalyst; passivating the Cu-MEL precursor with an amine compound solution, thereby obtaining the Cu-MEL zeolite confined catalyst.

5. The preparation method according to claim 4, characterized in that, The basic substance comprises ammonia and / or ethylenediamine.

6. The production method according to claim 4 or 5, characterized by, The molar ratio of the Cu salt to the basic substance is 1:4-10.

7. The preparation method according to claim 4, characterized in that, The firing temperature is 400-600℃, and the firing time is 3-6 h.

8. The preparation method according to claim 4, characterized in that, The amine compound in the amine compound solution comprises aniline and / or alkyl aniline.

9. The production method according to claim 4 or 8, characterized by, The molar ratio of the amine compound in the amine compound solution to the Cu salt is 1-5:

1.

10. Use of the Cu-MEL zeolite confined catalyst according to any one of claims 1-3 or the Cu-MEL zeolite confined catalyst prepared by the preparation method according to any one of claims 4-9 in the catalytic dehydrogenation of ethanol to prepare acetaldehyde.

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