A catalyst and its preparation and application

Abstract

The invention discloses a catalyst and its preparation and application. The catalyst comprises alumina and a copper-containing active component and a nickel-containing active component loaded on the surface of the alumina. The preparation method thereof is as follows: copper nitrate and nickel nitrate are mixed and dissolved in water to obtain a nitrate mixture solution; the nitrate mixture solution is loaded on the surface of the alumina carrier and roasted at a high temperature to obtain a second intermediate; the second intermediate is appropriately reduced to obtain a catalyst. The catalyst can be used in catalyzing the synthesis of high-carbon alcohols from ethanol and butanol. The invention has extremely high selectivity and conversion rate, and the single-pass conversion rate can basically reach more than 99%; the invention has high stability and activity, and can directly convert ethanol and butanol into high-carbon alcohols in a reactor, without the need for two-step reaction and external hydrogenation conditions, thereby reducing the complexity of the reaction; at the same time, the reaction products are mainly n-hexanol and isooctyl alcohol, thereby reducing the difficulty of subsequent product separation.

Description

Technical Field

[0001] The invention relates to a catalyst and a preparation and application thereof, and in particular to a catalyst for efficiently catalyzing the synthesis of higher carbon alcohols from ethanol and butanol and a preparation and application thereof. Background Art

[0002] The main methods for synthesizing high-carbon alcohols include oil hydrogenation, Ziegler process, and carbonyl synthesis, i.e., olefin hydroformylation. Oil hydrogenation uses natural oils as raw materials, and the product is straight-chain even-numbered alcohols; the Ziegler process uses ethylene as raw material and triethylaluminum to synthesize to produce C 2-20 Or higher even-numbered carbon atom straight-chain primary alcohols; high olefin hydroformylation can produce different straight-chain alcohols, as well as isomeric alcohols. High olefin hydroformylation is the main method for synthesizing high-carbon alcohols and high-carbon isomeric alcohols. The current high-carbon alcohol synthesis technology has problems such as long process, complex technology, limited raw materials and production scale. Therefore, by designing a method for directly synthesizing high-carbon alcohols from ethanol and butanol, on the one hand, it can solve the problem of the development of the downstream industry of coal-based ethanol, and on the other hand, it overcomes the shortcomings of the traditional petroleum-based industrial production technology of high-carbon alcohols, such as long production process, low product purity, and expensive raw materials.

[0003] Existing high-carbon alcohol synthesis reaction includes two-step reaction of dehydrogenation and hydrogenation. Existing catalysts are only used for catalytic hydrogenation reaction under external hydrogenation conditions, and do not have the ability of combined catalytic dehydrogenation and hydrogenation reaction, and cannot be used for one-step direct synthesis of high-carbon alcohols. For example, Chinese patent CN112547069A discloses a copper-nickel catalyst, which is prepared by boron-modified alumina carrier loaded with copper and nickel, and is used to catalyze methyl isobutyl ketone hydrogenation to prepare methyl isobutyl alcohol. The catalyst in this patent uses fully reduced metallic copper and nickel as catalytic active components, and the performance of its hydrogenation catalytic activity depends on the addition of boron. Boron can promote the dispersion of active metal components on the alumina carrier of borax modification, strengthen the interaction between copper and nickel and alumina, and then improve the hydrogenation catalytic activity. It can be seen that the hydrogenation catalyst relies on copper and nickel with higher reduction as active components and relies on the addition of boron to have higher selectivity and catalytic activity, and both are indispensable. In addition, as a hydrogenation catalyst, this catalyst can only catalyze the hydrogenation reaction of ketone substances under external hydrogenation conditions, and cannot jointly catalyze dehydrogenation and hydrogenation reactions. It also cannot catalyze the direct one-step synthesis of high-carbon alcohols from low-carbon alcohol raw materials in the absence of hydrogen.

[0004] Chinese patent CN111217673A discloses a method for high-energy utilization of ethanol, which uses ethanol as a raw material to realize the conversion of ethanol into a higher-carbon alcohol product with higher energy density on a catalyst; the catalyst active components of this method are A and B, A is one or more of iron, cobalt, nickel, copper, ruthenium, rhodium, palladium, iridium, and platinum, and B is one or more of cerium, magnesium, zinc, lanthanum, calcium, and aluminum. The catalyst in this patent relies on rare earth elements such as cerium and lanthanum to realize the direct synthesis of high-carbon alcohols from ethanol. Once these key elements are missing, the catalytic activity of the catalyst will be greatly reduced or even lost. In addition, the nickel and copper elements in this patent have been reduced by a relatively high concentration (10%) of hydrogen, and the copper and nickel elements with a relatively high reduction degree synergistically enhance the activity of the catalyst with the rare earth elements, realizing the direct synthesis of high-carbon alcohols from ethanol as a raw material. However, the conversion rate of the catalyst for ethanol is low, and the highest conversion rate is only 60.9%. Moreover, the patent only discloses that the raw material for the synthesis of high-carbon alcohols is a single ethanol, and it is unknown whether the catalyst can maintain its conversion rate when the raw material is other low-carbon alcohols. Summary of the invention

[0005] Purpose of the invention: The purpose of the present invention is to provide a catalyst for efficiently catalyzing the synthesis of higher carbon alcohols from ethanol and butanol. Another purpose of the present invention is to propose a method for preparing the catalyst, solving the problem of how to prepare the catalyst. The third purpose of the present invention is to propose an application of the above catalyst in catalyzing the synthesis of higher carbon alcohols from ethanol and butanol, solving the problem of how to catalytically prepare n-hexanol and isooctyl alcohol using ethanol and butanol as raw materials.

[0006] Technical solution: The catalyst described in the present invention comprises alumina and a copper-containing active component and a nickel-containing active component loaded on the surface of the alumina, wherein the copper-containing active component is an incomplete reduction product of copper oxide, and the nickel-containing active component is an incomplete reduction product of nickel oxide.

[0007] The catalyst of the present invention comprises a copper-containing active component and a nickel-containing active component through nickel and copper elements with a lower reduction degree and copper-nickel oxide, and a higher conversion rate can be obtained without relying on precious metals and rare earth elements.

[0008] Preferably, the molar ratio of copper to nickel in the catalyst is 1-10:1-10, the alumina has a particle size of 0.1-6 mm and a specific surface area of ​​200-500 m 2 / g, alumina particles with an average pore size of 0.5-10nm and a pore volume of 0.1-2.0mL / g.

[0009] In order to obtain the above catalyst, the present invention provides a method for preparing the catalyst, comprising the following steps:

[0010] (1) mixing copper nitrate and nickel nitrate and dissolving the mixture in water to obtain a nitrate mixture solution;

[0011] (2) loading the nitrate mixture solution onto the surface of the alumina support by a co-impregnation method to obtain a first intermediate;

[0012] (3) calcining the first intermediate at a high temperature to obtain a second intermediate;

[0013] (4) The second intermediate is subjected to a reduction reaction in a reducing gas to obtain an alumina-supported copper-nickel bimetallic oxide catalyst.

[0014] Preferably, in step (1), the molar ratio of copper nitrate to nickel nitrate is 1-10:1-10.

[0015] Preferably, in step (2), the co-impregnation method is to add alumina particles to the nitrate mixture solution at a material-liquid ratio of 1-5 g: 2-15 mL, and impregnate at 20-60° C. for 2-10 h to obtain the first intermediate.

[0016] Preferably, in step (3), the calcination temperature is 400-900° C., and the calcination time is 6-24 h.

[0017] Preferably, in step (4), the reducing gas is hydrogen with a concentration of 2-5%, the temperature of the reduction reaction is 100-300°C, and the reduction time is 3-12 hours. A lower concentration of hydrogen can control the reduction degree of copper and nickel elements at a lower level.

[0018] The present invention further applies the catalyst prepared by the preparation method to the reaction of catalyzing ethanol and butanol to synthesize higher carbon alcohols.

[0019] Preferably, the method for synthesizing higher alcohols using the above catalyst comprises the following steps:

[0020] (1) adding a catalyst to a mixed raw material liquid of ethanol and butanol and reacting under high temperature and high pressure;

[0021] (2) After the reaction is completed, the catalyst is removed by filtration, and the filtrate is distilled to obtain n-hexanol and isooctyl alcohol products, and the catalyst is reused.

[0022] Preferably, in step (1), the amount of the catalyst is 1-5wt% of the mixed raw material liquid, the mixed raw material liquid is composed of ethanol and n-butanol mixed in a volume ratio of 1-5:1-5, and the high temperature and high pressure reaction conditions are 150-300°C, 0.5-5MPa, and the reaction time is 3-48h. The above reaction can be carried out in a steel high-pressure slurry bed reactor.

[0023] Preferably, in step (2), the ratio of n-hexanol to isooctyl alcohol products is 1-10:1.

[0024] Beneficial effects: Compared with the prior art, the present invention has the following significant advantages:

[0025] 1. The present invention has extremely high selectivity and conversion rate, and the single-pass conversion rate can basically reach more than 99%;

[0026] 2. The present invention has high stability and activity, and can directly convert ethanol and butanol into high-carbon alcohols in the reactor without the need for two-step reaction and external hydrogenation conditions, thereby reducing the complexity of the reaction; at the same time, the reaction products are mainly n-hexanol and isooctyl alcohol, thereby reducing the difficulty of subsequent product separation; the catalyst can still maintain high catalytic activity and selectivity after being recycled and reused 20 times. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a scanning electron microscope image of the catalyst prepared in Example 1. DETAILED DESCRIPTION

[0028] The technical solution of the present invention is further described below in conjunction with the accompanying drawings.

[0029] Example 1: A method for preparing a catalyst is as follows:

[0030] (1) mixing copper nitrate and nickel nitrate and dissolving them in water to obtain a nitrate mixture solution, wherein the final concentration of the copper nitrate in the nitrate mixture solution is 2 mol / L, and the final concentration of the nickel nitrate is 4 mol / L;

[0031] (2) According to the material-liquid ratio of 1g:2mL, the particle size is 0.1mm and the specific surface area is 200m 2 / g, an average pore size of 10nm, and a pore volume of 0.1mL / g of alumina particles are added to a nitrate mixture solution and immersed at 20°C for 10h to obtain a first intermediate;

[0032] (3) calcining the first intermediate at 400° C. for 24 hours to obtain a second intermediate;

[0033] (4) The second intermediate was subjected to a reduction reaction in 2% hydrogen (the rest was nitrogen) at a temperature of 100° C. for 12 h to obtain an alumina-supported copper-nickel bimetallic oxide catalyst. The microstructure of the catalyst is as follows: Figure 1 shown.

[0034] The above catalyst is used to synthesize higher carbon alcohols as follows:

[0035] (1) mixing ethanol and n-butanol in a volume ratio of 1:5 to obtain a mixed raw material liquid;

[0036] (2) adding a catalyst to the mixed raw material liquid, the amount of the catalyst being 1 wt% of the mixed raw material liquid, and reacting in a steel high-pressure slurry bed reactor at 150° C. and 0.5 MPa for 48 hours;

[0037] (3) After the reaction is completed, the catalyst is removed by filtration, and the filtrate is distilled to obtain n-hexanol and isooctyl alcohol products, and the catalyst is reused.

[0038] Example 2: A method for preparing a catalyst is as follows:

[0039] (1) mixing copper nitrate and nickel nitrate and dissolving them in water to obtain a nitrate mixture solution, wherein the final concentration of the copper nitrate in the nitrate mixture solution is 0.5 mol / L, and the final concentration of the nickel nitrate is 5 mol / L;

[0040] (2) According to the material-liquid ratio of 5g:15mL, the particle size is 6mm and the specific surface area is 500m 2 / g, an average pore size of 0.5nm, and a pore volume of 2.0mL / g of alumina particles are added to a nitrate mixture solution and immersed at 60°C for 2h to obtain a first intermediate;

[0041] (3) calcining the first intermediate at 900° C. for 6 h to obtain a second intermediate;

[0042] (4) The second intermediate is subjected to a reduction reaction in 5% concentration of hydrogen (the rest is nitrogen) at a temperature of 300° C. and a reduction time of 3 h to obtain an alumina-supported copper-nickel bimetallic oxide catalyst.

[0043] The above catalyst is used to synthesize higher carbon alcohols as follows:

[0044] (1) mixing ethanol and n-butanol at a volume ratio of 5:1 to obtain a mixed raw material liquid;

[0045] (2) adding a catalyst to the mixed raw material liquid, the amount of the catalyst being 1.5 wt % of the mixed raw material liquid, and reacting in a steel high-pressure slurry bed reactor at 300° C. and 5 MPa for 3 h;

[0046] (3) After the reaction is completed, the catalyst is removed by filtration, and the filtrate is distilled to obtain n-hexanol and isooctyl alcohol products, and the catalyst is reused.

[0047] Example 3: A method for preparing a catalyst is as follows:

[0048] (1) mixing copper nitrate and nickel nitrate and dissolving them in water to obtain a nitrate mixture solution, wherein the final concentration of the copper nitrate in the nitrate mixture solution is 4 mol / L, and the final concentration of the nickel nitrate is 2 mol / L;

[0049] (2) According to the material-liquid ratio of 3g:10mL, the particle size is 3mm and the specific surface area is 300m2 / g, an average pore size of 3nm, and a pore volume of 1.0mL / g of alumina particles are added to a nitrate mixture solution and immersed at 40°C for 6h to obtain a first intermediate;

[0050] (3) calcining the first intermediate at 600° C. for 12 h to obtain a second intermediate;

[0051] (4) The second intermediate is subjected to a reduction reaction in 3% hydrogen (the rest is nitrogen) at a temperature of 200° C. for 6 hours to obtain an alumina-supported copper-nickel bimetallic oxide catalyst.

[0052] The above catalyst is used to synthesize higher carbon alcohols as follows:

[0053] (1) mixing ethanol and n-butanol in a volume ratio of 3:4 to obtain a mixed raw material liquid;

[0054] (2) adding a catalyst to the mixed raw material liquid, the amount of the catalyst being 3 wt % of the mixed raw material liquid, and reacting in a steel high-pressure slurry bed reactor at 200° C. and 3 MPa for 12 h;

[0055] (3) After the reaction is completed, the catalyst is removed by filtration, and the filtrate is distilled to obtain n-hexanol and isooctyl alcohol products, and the catalyst is reused.

[0056] Embodiment 4: A method for preparing a catalyst is as follows:

[0057] (1) mixing copper nitrate and nickel nitrate and dissolving them in water to obtain a nitrate mixture solution, wherein the final concentration of the copper nitrate in the nitrate mixture solution is 4 mol / L, and the final concentration of the nickel nitrate is 0.4 mol / L;

[0058] (2) According to the material-liquid ratio of 3g:5mL, the particle size is 0.5mm and the specific surface area is 300m 2 / g, an average pore size of 4nm, and a pore volume of 1.5mL / g of alumina particles are added to the nitrate mixture solution and immersed at 30°C for 8h to obtain a first intermediate;

[0059] (3) calcining the first intermediate at 500° C. for 8 h to obtain a second intermediate;

[0060] (4) The second intermediate is subjected to a reduction reaction in 4% hydrogen (the rest is nitrogen) at a temperature of 300° C. for 5 hours to obtain an alumina-supported copper-nickel bimetallic oxide catalyst.

[0061] The above catalyst is used to synthesize higher carbon alcohols as follows:

[0062] (1) mixing ethanol and n-butanol in a volume ratio of 2:3 to obtain a mixed raw material liquid;

[0063] (2) adding a catalyst to the mixed raw material liquid, the amount of the catalyst being 2 wt % of the mixed raw material liquid, and reacting in a steel high-pressure slurry bed reactor at 250° C. and 2 MPa for 10 h;

[0064] (3) After the reaction is completed, the catalyst is removed by filtration, and the filtrate is distilled to obtain n-hexanol and isooctyl alcohol products, and the catalyst is reused.

[0065] Comparative Example 1: The rest is the same as Example 3, except that:

[0066] In the catalytic synthesis of higher carbon alcohols, ethanol is used as the raw material to replace n-butanol, that is, the synthetic raw material is only ethanol.

[0067] Comparative Example 2: The rest is the same as Example 3, except that:

[0068] In the catalytic synthesis of higher carbon alcohols, n-butanol is used as the raw material to replace ethanol, that is, the synthetic raw material is only n-butanol.

[0069] Comparative Example 3: The rest is the same as Example 3, except that:

[0070] Nickel nitrate was used instead of copper nitrate.

[0071] Comparative Example 4: The rest is the same as Example 3, except that:

[0072] Copper nitrate was used instead of nickel nitrate.

[0073] Comparative Example 5: The rest is the same as Example 3, except that:

[0074] In the catalytic synthesis of higher carbon alcohols, propanol is used as the raw material to replace n-butanol.

[0075] Comparative Example 6: The rest is the same as Example 3, except that:

[0076] In the catalytic synthesis of higher carbon alcohols, propanol is used as the raw material to replace ethanol.

[0077] The ethanol conversion rate, n-butanol conversion rate and product selectivity of the catalysts in Examples 1-4 and Comparative Examples 1-4 were measured, and the results were as follows:

[0078] Table 1 Catalytic performance of different catalysts

[0079]

[0080]

[0081] As can be seen from the results in Table 1, the catalyst in the present invention has good catalytic activity only for the mixture of ethanol and n-butanol, and can efficiently catalyze the synthesis of higher carbon alcohols. However, for the synthesis reaction with single ethanol or n-butanol or other low-carbon alcohols as raw materials, the catalytic activity is low and the conversion rate is low, which is not suitable for direct catalytic synthesis of higher carbon alcohols with single ethanol or n-butanol as raw materials. In addition, when the active metal element is only copper or nickel, the catalytic activity is greatly reduced, indicating that copper and nickel have a synergistic effect on improving the catalytic activity.

[0082] Comparative Example 7: The catalyst prepared in Example 3 was used to hydrogenate n-hexanone to prepare n-hexanol, and the method was as follows:

[0083] The catalyst was loaded into a fixed bed reactor, and hydrogen and n-hexanone were mixed at a molar ratio of 5:1 and then fed into the reactor for hydrogenation reaction in the catalyst bed. The amount of catalyst was 3wt% of n-hexanone. The reaction conditions were: reaction temperature 120°C, reaction pressure 1.6MPa, space velocity 0.5h -1 .

[0084] The detection showed that the conversion rate of n-hexanone was 5.9%.

[0085] The catalyst of the present invention has low catalytic activity for the hydrogenation reaction of ketones by external hydrogenation.

[0086] Embodiment 5: The rest is the same as Embodiment 3, except that:

[0087] The reduction reaction is carried out within the hydrogen concentration range of 0.5-25%, with the hydrogen concentration in the catalyst preparation step (4) being used as a variable.

[0088] The catalysts prepared under different hydrogen concentrations were used to synthesize higher alcohols, and the conversion rates and product selectivities of ethanol and n-butanol were measured. The results are shown in Table 2:

[0089] Table 2 Catalytic performance of catalysts prepared under different hydrogen concentrations

[0090]

[0091]

[0092] The results in Table 2 show that at higher hydrogen concentrations, the degree of reduction of copper-nickel oxide is also higher, resulting in a significant decrease in the catalytic performance of the catalyst for the synthesis of higher carbon alcohols from ethanol and butanol. However, too low a hydrogen concentration cannot produce enough copper-nickel reduction products. Only in the metal active components reduced within the concentration range of 1.5-5%, the ratio of copper-nickel oxide to reduction products is appropriate, so that the catalytic performance of the catalyst is significantly improved.

Claims

1. Use of a catalyst in catalyzing the synthesis of higher alcohols from ethanol and n-butanol, characterized in that: The catalyst comprises aluminum oxide and a copper-containing active component and a nickel-containing active component supported on the surface of the aluminum oxide, wherein the copper-containing active component is an incomplete reduction product of copper oxide, and the nickel-containing active component is an incomplete reduction product of nickel oxide; The molar ratio of copper to nickel in the catalyst is 1-10:1-10, the alumina has a particle size of 0.1-6 mm and a specific surface area of ​​200-500 m 2 / g, alumina particles with an average pore size of 0.5-10nm and a pore volume of 0.1-2.0mL / g; The preparation method of the catalyst comprises the following steps: (1) mixing copper nitrate and nickel nitrate and dissolving them in water to obtain a nitrate mixture solution; (2) loading the nitrate mixture solution onto the surface of an alumina support by a co-impregnation method to obtain a first intermediate; (3) calcining the first intermediate at a high temperature to obtain a second intermediate; (4) subjecting the second intermediate to a reduction reaction in a reducing gas to obtain an alumina-supported copper-nickel bimetallic oxide catalyst; In step (4), the reducing gas is hydrogen with a concentration of 2-5%, the temperature of the reduction reaction is 100-300° C., and the reduction time is 3-12 hours.

2. The use according to claim 1, characterized in that: In step (1), the molar ratio of copper nitrate to nickel nitrate is 1-10:1-10.

3. The use according to claim 1, characterized in that: In step (2), the co-impregnation method is to add alumina particles to the nitrate mixture solution at a material-liquid ratio of 1-5 g: 2-15 mL, and impregnate at 20-60° C. for 2-10 hours to obtain the first intermediate.

4. The use according to claim 1, characterized in that: In step (3), the calcination temperature is 400-900°C and the calcination time is 6-24 h.

5. The use according to claim 1, characterized in that: The steps include: (1) Adding the catalyst to a mixed raw material liquid of ethanol and n-butanol, and reacting under high temperature and high pressure; (2) After the reaction is completed, the catalyst is filtered out and the filtrate is distilled to separate n-hexanol and isooctyl alcohol products, and the catalyst is reused.

6. The use according to claim 5, characterized in that: In step (1), the amount of the catalyst used is 1-5wt% of the mixed raw material liquid, the mixed raw material liquid is composed of ethanol and n-butanol mixed in a volume ratio of 1-5:1-5, and the high temperature and high pressure reaction conditions are 150-300°C, 0.5-5MPa, and the reaction time is 3-48h.

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