CN117583017A - Application of copper-based catalyst in monohydric alcohol dehydrogenation reaction - Google Patents

Application of copper-based catalyst in monohydric alcohol dehydrogenation reaction Download PDF

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CN117583017A
CN117583017A CN202311578880.6A CN202311578880A CN117583017A CN 117583017 A CN117583017 A CN 117583017A CN 202311578880 A CN202311578880 A CN 202311578880A CN 117583017 A CN117583017 A CN 117583017A
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copper
catalyst
reaction
hydrothermal
based catalyst
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郭晋
庞纪峰
郑明远
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Dalian Institute of Chemical Physics of CAS
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    • B01J29/00—Catalysts comprising molecular sieves
    • B01J29/03—Catalysts comprising molecular sieves not having base-exchange properties
    • B01J29/0308—Mesoporous materials not having base exchange properties, e.g. Si-MCM-41
    • B01J29/0316—Mesoporous materials not having base exchange properties, e.g. Si-MCM-41 containing iron group metals, noble metals or copper
    • B01J29/0333—Iron group metals or copper
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    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
    • B01J23/70—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of the iron group metals or copper
    • B01J23/72—Copper
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J29/00—Catalysts comprising molecular sieves
    • B01J29/04—Catalysts comprising molecular sieves having base-exchange properties, e.g. crystalline zeolites
    • B01J29/041—Mesoporous materials having base exchange properties, e.g. Si/Al-MCM-41
    • B01J29/042—Mesoporous materials having base exchange properties, e.g. Si/Al-MCM-41 containing iron group metals, noble metals or copper
    • B01J29/044—Iron group metals or copper
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    • C07C45/002—Preparation of compounds having >C = O groups bound only to carbon or hydrogen atoms; Preparation of chelates of such compounds by dehydrogenation
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Abstract

The invention discloses an application of a copper-based catalyst in a monohydric alcohol dehydrogenation reaction, which belongs to the technical field of bioenergy chemical industry. The method has the advantages of simple operation, low catalyst cost, economy, practicability, high monoaldehyde and ketone production efficiency, low energy consumption and the like.

Description

Application of copper-based catalyst in monohydric alcohol dehydrogenation reaction
Technical Field
The invention belongs to the technical field of bioenergy chemical industry, and particularly relates to application of a copper-based catalyst in monohydric alcohol dehydrogenation reaction.
Background
Monohydric alcohol including ethanol, n-propanol, etc. is an important platform compound, and has the advantages of rich yield, wide sources, etc. Compared with the method, the monoaldehyde compound is difficult to prepare by a conventional method, and has the defects of pollution in the synthesis process, equipment corrosion, high carbon emission and the like. Development of a novel synthesis process for realizing green preparation of aldehyde compounds is needed.
Taking ethanol as an example: with the rapid development of fermentation technology, ethanol has become a novel bulk energy chemical platform compound. In 2018, ethanol yields exceeded 600 hundred million liters and increased at a rate of 4% -5% per year. The ethanol is mainly used for adding oil products at present, so that the fuel oil is partially replaced. However, ethanol is limited in the amount of oil added to existing engines, typically less than 10%, based on current engine safety and energy density limitations. In addition, the global electric vehicle technology is rapidly developed, the fuel oil demand is gradually reduced, and the development and application of ethanol are severely restricted by the series of factors.
Acetaldehyde is an important aliphatic compound, is a key raw material for manufacturing chemicals such as acetic acid, peracetic acid, pentaerythritol, pyridine and the like, and has high application value.
At present, acetaldehyde is mainly prepared by adopting an ethylene oxidation method, and has the defects of non-renewable raw materials and the like. Compared with the method, the method for converting ethanol into acetaldehyde through one-step catalysis has the advantages of high atom economy, simple process and the like.
In the research of ethanol catalytic dehydrogenation, the catalyst carrier and the preparation method have substantial influence on the reaction activity and stability of the catalyst, and most of the catalysts still have the problems of requiring toxic auxiliary agents, poor stability and the like. For example Tu et al [ document 1J. Chem. Tech. Biotechnol,1994,59:141-147; document 2J.mol.Catal.,1994,89:179-190]Cu is used as an active component, and toxic Cr 2 O 3 Is an auxiliary agent, and is prepared by a coprecipitation method and used for ethanol dehydrogenation reaction performance. It was found that the acid-base nature of the metal oxide promoter severely affected the activity of the catalyst for dehydrogenation reactions when the molar ratio of Cr/Cu wasAt 4/40, the catalyst activity was the highest. Chang et al [ document 3appl. Catalyst. A: general,2003, 246:253-264; literature 4 appl.catalyst.a: general,2005,288:53-61]Cu is used as an active component, and a series of catalysts are prepared by adopting an impregnation method and an ion exchange method and are used for alcohol dehydrogenation reaction. The result shows that rice husk is better than commercial silica gel as a carrier, and the ion exchange method has higher catalyst stability and still has deactivation phenomenon. Lu et al [ document 5ChemCatChem 2017,9 (3), 505-510; document 6ChemCatChem 2019,11,481-487;]a series of carbon-supported copper-based catalysts are synthesized for alcohol dehydrogenation reaction, so that good alcohol conversion rate and acetaldehyde selectivity are obtained, but the stability of the catalyst is poor and is generally lower than 500 minutes. Liu Gong super et al [ Chinese patent publication No. CN 103127945B ]]Copper is loaded on SiO 2 、Al 2 O 3 、ZrO 2 And on the carrier, the catalytic dehydrogenation of ethanol is realized by adopting P modification, so that the selectivity of the acetaldehyde is 98%. However, the catalyst still has the defects of poor activity and the like, the ethanol conversion rate is lower under the same conditions, and the stability of the catalyst is poor.
Similarly, the existing copper-based catalyst for the dehydrogenation reaction of monohydric alcohols such as propanol and butanol has similar problems, and the unification of the reaction activity and the stability is difficult to realize. Therefore, there is a need to develop highly stable catalysts to achieve direct dehydrogenation of monohydric alcohols.
Disclosure of Invention
The invention aims to provide preparation and application of a copper-based catalyst. The method has the advantages of simple operation, high stability, low catalyst cost, economy, practicability, high acetaldehyde production efficiency, low energy consumption and the like.
In order to achieve the above purpose, the technical scheme of the invention is as follows:
the catalyst is prepared by a hydrothermal synthesis method, and the method comprises the following steps:
(1) Preparing a precursor: dissolving copper salt, a silicon precursor, a template agent and an auxiliary agent in water, and fully stirring; the auxiliary agent is at least one of propylene diamine, butanediamine, ethylamine, diethylamine, triethylamine, ammonia water, ethylenediamine, ammonium nitrate and ammonium carbonate;
(2) And (3) carrying out hydrothermal treatment: transferring the mixed solution into a hydrothermal kettle, and performing hydrothermal synthesis by dynamic stirring;
(3) Post-treatment: filtering, washing, drying, roasting and reducing the precursor after the hydrothermal treatment to obtain a copper-based catalyst;
copper-based catalyst is used for the direct dehydrogenation reaction of monohydric alcohol, and the monohydric aldehyde and hydrogen are obtained through catalytic conversion in a fixed bed reactor. When the raw materials are isopropanol and 2-butanol, acetone and methyl ethyl ketone are obtained by catalysis.
Further, in the technical scheme, the copper salt is at least one of copper nitrate, copper chloride, copper acetate and copper sulfate, and the mass concentration of copper in the copper salt solution is between 0.2% and 20%.
Further, in the technical scheme, the mixed solution is transferred into a hydrothermal kettle for dynamic hydrothermal synthesis, the rotating speed of the hydrothermal kettle is 20-100 rpm, preferably 50-100 rpm, the hydrothermal temperature is 90-200 ℃, and the hydrothermal time is 10-80 hours.
Further, in the above technical scheme, the silicon precursor is at least one of tetraethoxysilane, sodium silicate, silica sol and tetramethylsilane.
Further, in the above technical scheme, the template agent is at least one selected from ethylamine, ethylenediamine, diethylamine, triethylamine, 1, 6-hexamethylenediamine, tetrapropylammonium hydroxide, tetramethylammonium hydroxide, benzyltrimethylammonium hydroxide, hexamethyldiammonium hydroxide, P123, cetyltrimethylammonium bromide, tetrabutylammonium bromide, hexamethyleneimine, and cetyltriethylammonium bromide.
Further, in the technical scheme, during the precursor preparation process, firstly copper salt is dissolved in aqueous solution, then auxiliary agent is added, and mixed transparent mixed solution is obtained by stirring; then adding a silicon source and a template agent, and stirring for 0.5-12 hours to obtain a mixed solution.
Further, in the above technical scheme, the temperature of calcination in the post-treatment is independently selected from 300 to 700 ℃; the baking atmosphere is selected from air; the reduction condition is 200-400 ℃ for 0.5-6 hours; the reducing atmosphere is hydrogen, methane or mixed gas; the mixed gas refers to the mixture of one of hydrogen and methane and at least one of nitrogen, argon and helium; the copper-based catalyst comprises a carrier and an active component copper; the copper content of the copper-based catalyst is 0.5-20wt%.
Further, in the technical scheme, the copper-based catalyst is used for catalyzing the reaction of preparing monoaldehyde, ketone and hydrogen by dehydrogenating monohydric alcohol, and the reaction adopts a fixed bed as a reactor; the monohydric alcohol comprises one of ethanol, propanol, isopropanol, butanol, isobutanol, amyl alcohol, hexanol, heptanol and octanol, the reaction pressure is 0.1-1 MPa, and the reaction temperature is 120-320 ℃; the mass airspeed of the catalytic reaction is 0.1 to 20 hours -1 The method comprises the steps of carrying out a first treatment on the surface of the The reaction is carried out without carrier gas, or the carrier gas is at least one of nitrogen, argon, helium, nitrous oxide and carbon dioxide.
Further, in the technical scheme, the selectivity of monoaldehyde and ketone is more than 90%, the selectivity of hydrogen is more than 90%, the catalyst stably runs for more than 300 hours, and the bed pressure change is less than 0.1MPa. Optionally, the copper-based catalyst is granulated, the particle size is 0.1-10 cm, and the axial crushing strength is 1-50 Kg/cm.
The invention has the following advantages:
1. the invention provides a preparation method of a copper-based catalyst, and the copper-based catalyst is used for alcohol dehydrogenation reaction, the catalyst prepared by the method can obviously improve the yield of acetaldehyde, reduce the generation of byproducts in the reaction process, and obviously improve the stability and service life of the catalyst.
2. The method uses bioethanol as a reactant to prepare the acetaldehyde, and has the advantages of rich ethanol reserves, sufficient sources, large yield, environmental friendliness and no pollution; acetaldehyde produced by the ethanol dehydrogenation reaction has wide application in the fields of fuel, chemicals and the like.
3. The copper-based catalyst prepared by the invention has the following structural advantages: a) The template agent has wide selection range, and can obtain a low-cost silicon-based carrier; b) The copper-based catalyst has a microporous and mesoporous hierarchical pore structure, and can promote the diffusion, adsorption and desorption of molecular reactants.
4. The copper-based catalyst provided by the invention is easy to prepare, low in cost and good in stability, and when being used for the dehydrogenation reaction of monohydric alcohols such as ethanol, the product is easy to separate and use, the whole process has good economical efficiency and practicability, meets the requirement of sustainable development, and has important economic value and industrialization prospect in biomass conversion.
5. In the preparation process of the catalyst, the auxiliary agent can stabilize copper ions, so that the copper ions can be embedded into the molecular sieve in the crystallization process.
Drawings
FIG. 1 is a graph of the adsorption and desorption of the Cu@MFI-in situ catalyst prepared in example 1.
FIG. 2 is a STEM map of Cu@MFI-in situ prepared in example 1.
Detailed Description
The present invention will be described in detail by way of examples, which should not be construed as limiting the scope of the invention. The examples give several typical catalyst preparation methods, but the specific process conditions are not limited to the parameters given in the examples.
The invention provides a preparation and application method of a stable copper-based catalyst, wherein the copper-based catalyst is prepared by a hydrothermal method. Firstly, copper salt is dissolved in water, an auxiliary agent is added to prepare a mixed solution, then a silicon source and a template agent are added, and the copper-based catalyst precursor is obtained through full stirring, wherein the copper content is 0.5-20wt%. Then, transferring the precursor into a hydrothermal kettle, carrying out dynamic stirring hydrothermal treatment, and roasting and reducing to obtain the copper-based catalyst. The catalyst is used in the direct dehydrogenation reaction of ethanol, the reaction is carried out on a fixed bed, the reaction atmosphere is at least one or more than two of nitrogen, argon, helium, nitrous oxide and carbon dioxide, the reaction temperature is more than or equal to 120 ℃, the selectivity of acetaldehyde is more than 90%, and the catalyst is stably operated for more than 300 hours.
Example 1 preparation of Cu@MFI-in situ catalyst
Step 1: preparation of precursor I
Copper nitrate 0.48g was weighed, added to a beaker containing 35.7mL of distilled water, stirred until completely dissolved, added with 2.4g of an auxiliary agent (ethylenediamine), stirred at 25℃for 0.5h, then added with 20.8g of tetraethyl orthosilicate and 15.3g of a template agent (tetrapropylammonium hydroxide), and stirred at 25℃for 12h to obtain a mixed solution precursor I.
Step 2: preparation of precursor II by hydrothermal method
Transferring the precursor I prepared in the step 1 into a Teflon lining autoclave, transferring the hydrothermal kettle into a homogeneous reactor, adjusting the rotating speed to 100r/min (rpm), and keeping the hydrothermal reaction at 100 ℃ for 72h; after crystallization, the solid product was recovered by filtration, washed three times with water and the sample was dried overnight in an oven at 100 ℃ to give solid precursor II.
Step 3: preparation of copper-based catalysts
Roasting the precursor II obtained in the step 2 in air for 4 hours at 550 ℃, transferring the precursor II into a mixed atmosphere of hydrogen and nitrogen (the volume content of the hydrogen is 5%), reducing the precursor II at 300 ℃ for 1 hour, and passivating the precursor II for 12 hours in a mixed atmosphere of oxygen and nitrogen (the volume content of the oxygen is 1%) at 25 ℃ to obtain the copper-based catalyst Cu@MFI-in situ. All MFI structures in this application are Silicalite-1.
Cu@MFI-in situ was subjected to nitrogen adsorption desorption and STEM test, and the results are shown in FIGS. 1 and 2. From the figure, it can be seen that the MFI carrier has multi-stage pores (micropores and mesopores), the active component copper particles are uniformly dispersed in the carrier, and no particle aggregation is seen.
EXAMPLE 2 preparation of Cu@SiO-1 catalyst
The difference from example 1 is that the auxiliary agent ethylenediamine in step 1 is replaced with ammonia water, the silicon source is replaced with sodium silicate, the hydrothermal temperature in step 2 is replaced with 190 ℃, the rotating speed of the hydrothermal kettle is adjusted to 80r/min, the hydrothermal time is replaced with 12h, and finally the catalyst Cu@SiO1 is obtained, wherein the load of Cu is 2.0wt%.
EXAMPLE 3 preparation of Cu@SBA-15
The difference from example 1 is that the template agent of step 1 is replaced with P123, hydrochloric acid is added after that, the hydrothermal time of step 2 is replaced with 24 hours, and finally the catalyst Cu@SBA-15 is obtained, wherein the load of Cu is 2.0wt%.
EXAMPLE 4 preparation of Cu@MCM-41 catalyst
The difference from example 1 is only that in step 1, HCl was added to the mixed solution i, the template agent was cetyltrimethylammonium bromide, the temperature of the hydrothermal synthesis in step 2 was replaced with 110 ℃ and the hydrothermal time was replaced with 48 hours; finally, the catalyst Cu@MCM-41 is obtained, and the Cu loading capacity is 2wt%.
EXAMPLE 5 preparation of Cu@ERB-1 catalyst
The difference from example 1 is that the template of step 1 is replaced by hexamethyleneimine and H is added 3 BO 3 The silicon source is replaced by HS-40 silica sol, the hydrothermal temperature and the hydrothermal time in the step 2 are replaced by 170 ℃ for 60 hours, and finally the catalyst Cu@ERB-1 is obtained, wherein the load of Cu is 2.0wt%.
Comparative example 1 preparation of Cu/MFI catalyst
The copper-based catalyst is synthesized by an isovolumetric impregnation method. First, an MFI (Silicalite-1) support was synthesized as in example 1 in the absence of copper precursor. Then, the catalyst is added into the prepared copper nitrate solution, fully stirred, dried, roasted and reduced to obtain the Cu/MFI catalyst. Wherein the Cu loading is 2.0wt%.
Comparative example 2 preparation of Cu/SiO 2 Catalyst
The only difference from comparative example 1 is that the carrier used is SiO 2 The carrier is finally obtained to obtain the catalyst Cu/SiO 2 Wherein the Cu loading is 2.0wt%.
Comparative example 3 preparation of Cu@MFI-in situ catalyst
The only difference from example 1 is that the dynamic synthesis of step 2 is replaced by a static synthesis, and finally the catalyst Cu@MFI-in situ static is obtained, wherein the loading of Cu is 2.0wt%.
Examples 6 to 15
Example 6 differs from example 1 only in that the amount of copper nitrate in step 1 is 0.145g; so that the loading of copper in the catalyst Cu@MFI-in situ obtained in the step 3 is 0.6wt%;
example 7 differs from example 1 only in that the amount of copper nitrate in step 1 is 0.241g; so that the loading of copper in the catalyst Cu@MFI-in situ obtained in the step 3 is 1.0wt%;
example 8 differs from example 1 only in that the amount of copper nitrate in step 1 is 0.966g; in the catalyst Cu@MFI-in situ obtained in the step 3, the copper loading is 4.0wt%;
example 9 differs from example 1 only in that the amount of copper nitrate in step 1 is 3.864g; in the catalyst Cu@MFI-in situ obtained in the step 3, the copper loading is 16.0wt%;
example 10 differs from example 1 only in that the auxiliary used in step 1 is diethylamine; the catalyst obtained in the step 3 is Cu@MFI-in situ-diethylamine;
example 11 differs from example 1 only in that the auxiliary used in step 1 is ethylamine; the catalyst obtained in the step 3 is Cu@MFI-in situ-ethylamine;
example 12 differs from example 1 only in that the hydrothermal pot used in step 2 has a rotational speed of 10rpm; the catalyst obtained in the step 3 is Cu@MFI-in situ-10rpm;
example 13 differs from example 1 only in that the hydrothermal pot used in step 2 has a rotational speed of 60 revolutions per minute; the catalyst obtained in the step 3 is Cu@MFI-in situ-60rpm;
example 14 differs from example 1 only in that the firing temperature and the reduction temperature in step 3 are 800 ℃ and 450 ℃, respectively; the catalyst obtained in the step 3 is Cu@MFI-in situ-800-450;
example 15 differs from example 2 only in that the auxiliary agent of step 1 is a mixture of ammonia water and ethylenediamine in a molar ratio of 1:1; the catalyst obtained in the step 3 is Cu@SiO-2.
Examples 16 to 20
Example 16, example 17, example 18, example 19, example 20 differ from example 1 only in that the template in step 1 is tetramethylammonium hydroxide, benzyltrimethylammonium hydroxide, hexamethyldiammonium hydroxide, hexamethyleneimine, 1, 6-hexamethylenediamine, respectively.
Comparative example 4
Comparative example 4 differs from example 1 only in that no auxiliary ethylenediamine was used in step 1.
Comparative example 5
Comparative example 5 differs from preparation example 1 only in the auxiliary methylamine in step 1.
Comparative example 6
Comparative example 6 differs from preparation example 1 only in that the auxiliary dimethylamine in step 1.
Application example 1
The catalytic conversion experiments were carried out in a fixed bed reactor under the following specific conditions: the catalysts prepared in examples 1 to 5 and comparative examples 1 to 3 were used for alcohol dehydrogenation reactions (ethanol concentration 98wt%, reaction temperature 250 ℃ C., reaction pressure normal pressure, reaction mass space velocity 0.55h, respectively -1 Copper loading of 2.0%) and catalyst usage of 0.2g, adding the catalyst into a fixed bed reactor, introducing nitrogen as carrier gas, pumping raw materials at a gas flow rate of 40mL/min, and analyzing the gas phase product by online gas chromatography.
The reaction results of the catalysts prepared in examples 1 to 5 and comparative examples 1 to 3, respectively, for the catalytic dehydrogenation of ethanol are shown in Table 1.
TABLE 1 different copper-based catalysts for the catalytic dehydrogenation reaction results of ethanol (24 h after reaction)
Table 1 compares the product variation of different copper-based catalysts for the alcohol dehydrogenation reaction. From the reaction data, it can be seen that the copper-based catalysts prepared in examples 1 to 5 by the hydrothermal in-situ synthesis have good reactivity and product selectivity compared to the purely impregnation catalysts (comparative example 1 and comparative example 2). In addition, the catalyst activity and product selectivity of dynamic synthesis were significantly higher than those of static hydrothermal synthesis catalyst (comparative example 3), which suggests that dynamic synthesis can improve the uniform dispersion of copper on the catalyst support, facilitating the smooth progress of this reaction. The purely mesoporous catalysts (mesoporous: cu@SBA-15 of example 3 and Cu@MCM-41 of example 4) were slightly less active than the multistage porous catalysts of comparative examples 1-2, which may be associated with mass transfer to the reaction substrate.
Application example 2
The specific reaction conditions were the same as in application example 1, and the results are shown in Table 2:
the catalysts prepared in examples 6 to 15 and comparative examples 5 and 6 were used in the reactions for the catalytic dehydrogenation of ethanol (ethanol concentration 98wt%, reaction temperature 250 ℃ C., reaction mass space velocity of 0.55h, respectively -1 ) The results are shown in Table 2.
TABLE 2 different Cu@MFI-in situ catalysts were used for the catalytic dehydrogenation conversion of ethanol (24 h after reaction)
As can be seen from the reaction data in table 2, the catalyst synthesis conditions significantly affect ethanol conversion and product selectivity. For example, when the rotation speed is slow in the hydrothermal process or the roasting temperature, the reduction temperature is too high, the ethanol conversion rate and the acetaldehyde selectivity may be lowered, which may be caused by the dispersion of copper. In addition, the selection of the auxiliary agent is particularly important, when the auxiliary agent is methylamine or dimethylamine, the ethanol conversion rate is obviously reduced in 24 hours, and the selectivity of acetaldehyde is also lower. In contrast, when the auxiliary agent is ethylenediamine or ethylamine, the catalyst exhibits higher activity and stability.
Application example 3
The Cu@MFI-in situ catalyst prepared with different templates was used for the catalytic dehydrogenation of ethanol (ethanol concentration 98wt%,250 ℃,2.0% Cu) as shown in Table 3, except for the reaction conditions specifically described in Table 3, which were the same as in application example 1.
TABLE 3 Cu@MFI-in situ catalysts prepared with different templates were used for the catalytic dehydrogenation of ethanol (24 h after reaction)
The template agent influences the pore structure of the catalyst, thereby changing the reactivity and selectivity of the final catalyst. When the low molecular organic amine is used as a template agent, the crystallinity of the generated carrier is low, so that the stability of the catalyst is poor. When macromolecular organic amine is used as a template agent, the ethanol conversion rate and the selectivity of acetaldehyde are improved to more than 90%, and the stability of the catalyst is greatly improved. The catalyst needs auxiliary agent and template agent to exist at the same time, and the selectivity of acetaldehyde is obviously reduced in the absence of the auxiliary agent, which indicates that the auxiliary agent plays an important role in catalyst synthesis.
Application example 4
The results of the catalytic dehydrogenation of ethanol using the catalyst Cu@MFI-in situ prepared in example 1 at different reaction temperatures are shown in Table 4, except for the reaction conditions specifically set forth in Table 4, which were the same as in application example 1.
TABLE 4 Cu@MFI-in situ catalyst at different reaction temperatures for ethanol catalytic dehydrogenation results (ethanol concentration 98wt%, results after 24h reaction, 2.0% Cu)
It was found (Table 4) that the ethanol conversion was gradually increased with increasing reaction temperature by changing the reaction temperature conditions, and 97.4% ethanol conversion and 97.7% acetaldehyde selectivity were achieved at 250℃under the same catalyst. However, when the temperature is higher than 320 ℃, side reactions such as dehydration and decomposition occur, and the selectivity is lowered.
Application example 5
The results of catalytic dehydrogenation of ethanol using the catalyst Cu@MFI-in situ prepared in example 1 at different space velocities under the same reaction conditions as in application example 1 except for the reaction conditions specifically described in Table 5 are shown in Table 5.
TABLE 5 Cu@MFI-in situ catalyst at different space velocities for ethanol catalytic dehydrogenation results (ethanol concentration 98wt%, results after 24h reaction, 2.0% Cu)
It was found (Table 5) that by varying the space velocity conditions, the ethanol conversion was slightly decreased with increasing space velocity under the same catalyst, and high selectivity of acetaldehyde over 95% was maintained at all times.
Application example 6
The results of the catalytic dehydrogenation of ethanol using the catalyst Cu@MFI-in situ prepared in example 1 for different raw materials are shown in Table 6, except for the reaction conditions specifically described in Table 6, which are the same as those of application example 1.
TABLE 6 Cu@MFI-in situ catalyst for catalytic dehydrogenation of monohydric alcohol (98 wt% concentration), after 24h reaction, 2.0% Cu, the product was the corresponding aldehyde or ketone
It was found that by varying the dehydrogenation of different monol feeds (Table 6, the same catalyst, the different monols all maintained high conversions and selectivities of greater than 90%.
Application example 7
Stability comparison of catalysts:
a stability experiment was performed using the Cu@MFI-in situ catalyst prepared in example 1 and the Cu@MFI-in situ solid catalyst of example 3, with a reaction time of 300 hours and other reaction conditions similar to those of application example 1. The results of the experiments of the invention compared with the results of the prior art are shown in Table 7
TABLE 7 comparison of the present invention with prior art alcohol dehydrogenation catalysts (98 wt% alcohol concentration, 250 ℃ C., space velocity 0.55 h) -1 )
By comparing with the literature (Table 7), the experimental results of the invention show that the experimental results have outstanding substantial progress in the aspect of the stability of the reactive catalyst, the catalyst of the invention is easy to prepare, the reaction condition is milder, the stability is ultra-high, and the practicability is high.
The foregoing is only a specific embodiment of the present invention, but the scope of the present invention is not limited thereto, and the present invention is not limited by the sequence of the embodiments, and any person skilled in the art can easily make changes or substitutions within the technical scope of the present invention. Therefore, the protection scope of the present invention should be limited by the claims.

Claims (9)

1. The application of a copper-based catalyst in a monohydric alcohol dehydrogenation reaction is characterized in that the catalyst is prepared by a hydrothermal synthesis method, and the method comprises the following steps:
(1) Preparing a precursor: dissolving copper salt, a silicon precursor, a template agent and an auxiliary agent in water, and fully stirring; the auxiliary agent is at least one of propylene diamine, butanediamine, ethylamine, diethylamine, triethylamine, ammonia water, ethylenediamine, ammonium nitrate and ammonium carbonate;
(2) And (3) carrying out hydrothermal treatment: transferring the mixed solution into a hydrothermal kettle, and performing hydrothermal synthesis by dynamic stirring;
(3) Post-treatment: filtering, washing, drying, roasting and reducing the precursor after the hydrothermal treatment to obtain a copper-based catalyst;
the copper-based catalyst is used for the direct dehydrogenation reaction of monohydric alcohol, and the monohydric aldehyde, ketone and hydrogen are obtained through catalytic conversion in a fixed bed reactor.
2. The use according to claim 1, wherein in the catalyst synthesis method, the copper salt is at least one of copper nitrate, copper chloride, copper acetate and copper sulfate, and the mass concentration of copper in the copper salt solution is between 0.2% and 20%.
3. The use according to claim 1, wherein in the catalyst synthesis process, the mixed solution is transferred to a hydrothermal reactor at a speed of 20-100 rpm, preferably 50-100 rpm, for a hydrothermal time of 10-80 hours at a hydrothermal temperature of 90-200 ℃.
4. The use according to claim 1, wherein in the catalyst synthesis process the silicon precursor is at least one of ethyl orthosilicate, sodium silicate, silica sol, tetramethylsilane.
5. The use according to claim 1, wherein in the catalyst synthesis method, the template agent is selected from at least one of ethylamine, ethylenediamine, diethylamine, triethylamine, 1, 6-hexamethylenediamine, tetrapropylammonium hydroxide, tetramethylammonium hydroxide, benzyltrimethylammonium hydroxide, hexamethyldiammonium hydroxide, P123, cetyltrimethylammonium bromide, tetrabutylammonium bromide, hexamethyleneimine, cetyltriethylammonium bromide.
6. The use according to claim 1, wherein in the catalyst synthesis method, the copper salt is first dissolved in the aqueous solution during the preparation of the precursor, then the auxiliary agent is added, and the mixed transparent mixed solution is obtained by stirring; then adding a silicon source and a template agent, and stirring for 0.5-12 hours to obtain a mixed solution.
7. The use according to claim 1, characterized in that in the catalyst synthesis process the temperature of calcination in the post-treatment is independently selected from 300-700 ℃; the baking atmosphere is selected from air; the reduction condition is 200-400 ℃ for 0.5-6 hours; the reducing atmosphere is hydrogen, methane or mixed gas; the mixed gas is the mixture of one of hydrogen and methane and at least one of nitrogen, argon and helium, and the copper-based catalyst comprises a carrier and active component copper; the copper content of the copper-based catalyst is 0.5-20wt%.
8. The use of claim 1, wherein the copper-based catalyst is used for catalyzing the dehydrogenation of monohydric alcohols to produce a catalystIn the reaction of the meta aldehyde, ketone and hydrogen, a fixed bed is adopted as a reactor in the reaction; the monohydric alcohol comprises one of ethanol, propanol, isopropanol, butanol, isobutanol, amyl alcohol, hexanol, heptanol and octanol, the reaction pressure is 0.1-1 MPa, and the reaction temperature is 120-320 ℃; the mass airspeed of the catalytic reaction is 0.1 to 20 hours -1 The method comprises the steps of carrying out a first treatment on the surface of the The reaction is carried out without carrier gas, or the carrier gas is at least one of nitrogen, argon, helium, nitrous oxide and carbon dioxide.
9. The use according to claim 8, characterized in that: the selectivity of the monoaldehyde and the ketone is more than 90%, the hydrogen selectivity is more than 90%, the catalyst stably runs for more than 300 hours, and the bed pressure change is less than 0.1MPa.
CN202311578880.6A 2023-11-23 2023-11-23 Application of copper-based catalyst in monohydric alcohol dehydrogenation reaction Pending CN117583017A (en)

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