CN108043411B

CN108043411B - Catalyst for preparing n-butanol by hydrogenating n-butyraldehyde and preparation method thereof

Info

Publication number: CN108043411B
Application number: CN201711284678.7A
Authority: CN
Inventors: 于海波; 李作金; 詹吉山; 初乃波; 黎源; 华卫琦
Original assignee: Wanhua Chemical Group Co Ltd; Wanhua Chemical Ningbo Co Ltd
Current assignee: Wanhua Chemical Group Co Ltd; Wanhua Chemical Ningbo Co Ltd
Priority date: 2017-12-07
Filing date: 2017-12-07
Publication date: 2020-07-28
Anticipated expiration: 2037-12-07
Also published as: CN108043411A

Abstract

The invention relates to a catalyst for preparing n-butanol by hydrogenating n-butyraldehyde and a preparation method thereof. The catalyst comprises copper oxide, zinc oxide and silica. The preparation method of the catalyst adopts a synchronous precipitation method, so that copper and zinc are precipitated at two different temperatures respectively to obtain two different pore channel structures, and a double-pore system is formed. The catalyst has the characteristics of high active component dispersion degree, good mass transfer/heat transfer performance and the like, has excellent activity and selectivity, reduces the generation of byproducts n-butyl n-butyrate and octanol, and improves the selectivity of n-butanol.

Description

Catalyst for preparing n-butanol by hydrogenating n-butyraldehyde and preparation method thereof

Technical Field

The invention specifically relates to a catalyst for preparing alcohol by aldehyde hydrogenation, specifically relates to a catalyst for preparing n-butyl alcohol by n-butyl aldehyde hydrogenation, and belongs to the technical field of catalysis.

Background

N-butyl alcohol is an important organic chemical raw material, is a solvent of various coatings and a raw material for preparing plasticizer dibutyl phthalate, is also used for preparing butyl acrylate, butyl acetate and ethylene glycol butyl ether, is used as an extracting agent of organic synthesis intermediates and biochemical drugs, and is also used for preparing surfactants.

The industrial preparation method of n-butanol mainly includes three methods of fermentation method, propylene oxo synthesis method and acetaldehyde aldol condensation method. In addition, n-butanol is also a by-product in the production of higher aliphatic alcohols from ethylene. The propylene carbonylation synthesis method has become the most important method for producing the n-butanol due to the characteristics of easily available raw materials, relatively low pressure of the carbonylation process, relatively mild reaction conditions and the like.

The propylene oxo-synthesis method is mainly characterized in that propylene, carbon monoxide and hydrogen are subjected to oxo-synthesis reaction by using a cobalt or rhodium catalyst to generate n-butyl aldehyde and iso-butyl aldehyde, and the n-butyl aldehyde is hydrogenated to obtain n-butyl alcohol. The n-butyraldehyde hydrogenation reaction process is a key process for producing n-butanol, and the catalyst is the core of the hydrogenation reaction.

Hydrogenation of n-butyraldehyde can be carried out in the gas phase using copper as catalyst, or in the liquid phase using nickel as catalyst. The gas phase method is widely applied due to low reaction pressure and simple process equipment, most of domestic butanol devices adopt a gas phase hydrogenation method, and the catalyst adopts a copper-zinc catalyst prepared by a precipitation method.

Catalysts for the vapor phase hydrogenation of n-butyraldehyde to produce n-butanol have been reported in many patents. Such as: CN1381311A discloses a copper-zinc-aluminum catalyst prepared by a coprecipitation method, and alkali metal/alkaline earth metal elements such as K, Ca, Na, Mg and Ba are added as an auxiliary agent. The catalyst is used at 130 ℃, 0.4MPa and the liquid-phase space velocity of n-butyl aldehyde of 0.36h^-1Under the reaction conditions, the conversion rate of the n-butyraldehyde is about 98 percent, and the selectivity of the n-butanol is about 99 percent.

DE4244273 discloses a Na₂The O modified Cu-Zn-Al catalyst is used in butyraldehyde gas phase hydrogenation. CN1050994A discloses a method for preparing a catalyst by adding a small amount of alkali metal and auxiliaries such as nickel and cobalt in a copper-zinc catalyst to improve the selectivity of the catalyst.

The patent disclosed in CN1695802A discloses a butyraldehyde hydrogenation catalyst is prepared by a fractional coprecipitation method, a coprecipitation method of aluminum and an auxiliary agent, a coprecipitation method of copper and zinc, and a mixing method of the two precipitates.

The butyraldehyde hydrogenation catalysts disclosed and reported above are copper-zinc catalysts prepared by a coprecipitation method, and the biggest problems are a series of problems of poor dispersion degree of active components, small catalyst pores, poor mass transfer/heat transfer performance, high generation amount of butyl butyrate serving as a byproduct, poor n-butanol selectivity and the like.

The main byproduct in the process of preparing the butanol by gas phase hydrogenation of the butyraldehyde is the butyl butyrate, the generation of the butyl butyrate is closely related to the composition, the acidity and the alkalinity and the mass transfer/heat transfer performance of the catalyst, and the generation of the butyl butyrate as the byproduct can be greatly promoted by the strong acidity and the poor heat transfer performance of the catalyst. Therefore, the improvement of the catalyst preparation method, the optimization of the catalyst pore structure and the acidity and alkalinity, and the improvement of the heat transfer and mass transfer performance of the catalyst are very important for preparing the butyraldehyde hydrogenation catalyst with high activity and high selectivity.

Disclosure of Invention

The invention aims to provide a catalyst for preparing n-butanol by hydrogenating n-butyraldehyde and a preparation method thereof.

In order to achieve the purpose, the invention adopts the technical scheme that:

a catalyst for preparing n-butanol by hydrogenating n-butyraldehyde comprises the following components: 24-50 wt% of copper oxide, 49-75 wt% of zinc oxide and 0.5-2 wt% of silicon dioxide, based on the weight of the catalyst.

Preferably, the catalyst composition prepared by the method of the present invention comprises: 28-45 wt% of copper oxide, 54-70 wt% of zinc oxide and 0.5-2 wt% of silicon dioxide, based on the weight of the catalyst.

More preferably, the catalyst composition prepared by the process of the present invention comprises: 30-45 wt% of copper oxide, 54-69 wt% of zinc oxide and 0.5-2 wt% of silicon dioxide, based on the weight of the catalyst.

A preparation method of a catalyst for preparing n-butanol by hydrogenating n-butyraldehyde comprises the following steps: according to the proportion,

(1) adding a pore-forming agent aqueous dispersion into a reactor A, adding a mixed solution containing copper salt, zinc salt and an auxiliary agent Si into the reactor A in parallel with an alkaline precipitator, and controlling the precipitation temperature of the A to be 60-80 ℃, preferably 65-75 ℃, and the pH value to be 6.5-8.0, preferably 6.8-7.5;

(2) adding a pore-forming agent aqueous dispersion into a reactor B, adding a mixed solution containing copper salt, zinc salt and an auxiliary agent Si into the reactor B in parallel with an alkaline precipitator, and controlling the precipitation temperature of the reactor B to be 45-60 ℃, preferably 48-58 ℃, and the pH value to be 6.5-8.0, preferably 6.8-7.5;

(3) mixing the obtained serosity in the A and the B, and then aging for 2-4h, wherein the aging temperature is controlled to be 65-80 ℃, and the optimal temperature is 68-78 ℃;

(4) filtering the slurry obtained in the step (3), and washing with an organic solvent to obtain a filter cake; and drying and roasting the filter cake, and then tabletting and forming to obtain the catalyst.

In the step (1) and the step (2), the sources of the pore-forming agent, the copper salt, the zinc salt and the auxiliary agent Si are respectively the same, and the amounts of the raw materials are respectively the same. For example, step (1) and step (2) both use equal weight of copper nitrate as the copper salt. The equivalents according to the invention can be distributed within the tolerances acceptable to the skilled worker, preferably, the ratio of the absolute value of the mass difference between step (1) and step (2) to the sum of the masses is greater than or equal to 0 and less than 2% for the same starting material; more preferably, the ratio of the absolute value of the mass difference to the sum of the masses of step (1) and step (2) is equal to 0 for the same starting material.

The pore-forming agent aqueous dispersion is prepared by dispersing a pore-forming agent in water. The pore-forming agent is selected from one or more of sesbania powder, methyl cellulose, microcrystalline cellulose and the like. The amount of pore-forming agent used in step (1) or step (2) is 0.25 to 7.5 wt%, preferably 0.5 to 5 wt%, more preferably 1 to 4 wt% based on the weight of the finally prepared catalyst.

In the invention, the pore-forming agent is added to serve as a crystal nucleus at the beginning of the reaction to induce the formation of a precursor of a copper-zinc type malachite structure, so that the dispersion degree of the catalyst active component copper is improved; in the roasting process, the pore-forming agent is oxidized and decomposed into gas which overflows, and a plurality of fine pore passages are formed in the catalyst, so that the pores of the catalyst are developed, the mass transfer/heat transfer performance of the catalyst is improved, and the activity and the selectivity of the catalyst are improved.

In the invention, the copper salt is selected from one or more of copper nitrate, copper chloride, copper acetate and the like; the zinc salt is selected from one or more of zinc nitrate, zinc chloride, zinc acetate and the like.

The auxiliary agent Si is selected from one or more of silica sol, sodium silicate, sodium aluminosilicate and the like.

The dosage of the auxiliary agent Si is converted into SiO₂Calculated, SiO₂0.5-2 wt% of the catalyst.

The addition of the auxiliary agent Si can promote the hydrogenolysis of the reaction by-product n-butyl butyrate into n-butyl alcohol, thereby effectively improving the selectivity of the catalyst.

The total concentration of metal ions in the mixed solution is 0.5-2 mol/L, and the molar ratio of copper ions to zinc ions is 1:3-1:1, preferably 1:2.5-1: 1.2.

In the present invention, the alkaline precipitant includes, but is not limited to, one or more of sodium carbonate, potassium carbonate, sodium bicarbonate, potassium bicarbonate, sodium hydroxide, potassium hydroxide, ammonium carbonate, ammonium bicarbonate, ammonia water, and the like. The alkaline precipitant is preferably used in the form of an aqueous solution having a concentration of 10 wt% to 20 wt%. The pH value of the precipitation process is regulated and controlled by regulating the dosage of the alkaline precipitator.

The organic solvent for washing in the step (4) of the present invention includes, but is not limited to, one or more of methanol, ethanol, ethylene glycol, and the like; washing until the conductivity of the washing liquid is less than 100 mu s/cm.

The volatile organic solvent is selected as the washing agent, and the molecules of the organic solvent are larger than water molecules, so that in the drying process, the volatilization of the organic solvent can make the pore channels of the catalyst larger and more loose, the pore channels of the catalyst are more loose, the mass transfer/heat transfer capacity is enhanced, and the activity and the selectivity of the catalyst can be effectively improved.

The drying temperature of the step (4) of the invention is 95-125 ℃, preferably 105-115 ℃, and the drying time is 4-16h, preferably 6-14 h.

The roasting temperature of the filter cake in the step (4) of the invention is 260-330 ℃, preferably 280-320 ℃, and the roasting time is 3-12h, preferably 4-8 h.

The catalyst prepared by the method adopts a synchronous precipitation method to precipitate copper and zinc at two different temperatures respectively to obtain two different pore channel structures to form a double-pore system, wherein the pore diameter range of a small pore is 2-5nm, and the pore volume of the small pore accounts for about 20-50%, preferably 30-45% of the total pore volume; the pore diameter range of the macropores is 10-20nm, the pore volume of the macropores accounts for about 40-60%, preferably 45% -55% of the total pore volume, the macropores are favorable for mass and heat transfer, and the hot spot temperature of the reaction is reduced, so that the generation of a main byproduct n-butyl butyrate is reduced; the small holes are beneficial to inhibiting the generation of octanol which is a byproduct of macromolecules. The two apertures are combined, so that the amount of byproducts in the reaction process is reduced, and the selectivity of the n-butyl alcohol is improved.

The catalyst prepared by the method has corresponding catalytic activity after reduction activation and is used for preparing n-butanol by gas phase hydrogenation of n-butyraldehyde.

The method for reducing and activating the prepared catalyst comprises the following steps: keeping the volume space velocity of nitrogen at 800-^-1The temperature of the reactor is raised to 130-160 ℃, the temperature is kept constant for 1-2h to remove the physical water adsorbed by the catalyst, then hydrogen is introduced, the volume ratio of the hydrogen to the nitrogen is 1:10, pre-reduction is carried out for 2h, then the ratio of the hydrogen is gradually increased to 1:5, 1:4, 1:2 and 1:1, the hot point temperature of the catalyst bed layer in the process is controlled not to exceed 220 ℃, finally the temperature of the reactor is raised to 220 ℃, the nitrogen is closed, and reduction is carried out for 3-6h under pure hydrogen atmosphere, so that the catalyst in the reduction state is obtained.

The catalyst after reduction activation is used for preparing n-butanol by gas phase hydrogenation of n-butyraldehyde at the reaction pressure of 0.4-0.5MPa, the reaction temperature of 120-160 ℃ and H₂The mol ratio of the aldehyde to the aldehyde is 10-30:1, and the space velocity of the feeding is 0.5-1.0ml_IBA·ml^-1 _Cat·h^-1。

The pressure in the invention is relative pressure.

The catalyst is used for preparing n-butanol by aldehyde gas phase hydrogenation, the active components of the catalyst are uniformly distributed, pores are developed, the catalyst has good heat transfer/mass transfer performance, and the catalyst has excellent activity and selectivity.

Detailed Description

The process of the present invention will be described in detail with reference to examples, but is not limited to the examples.

The raw materials of n-butyl aldehyde and hydrogenation liquid are analyzed by an Agilent 7890A gas chromatograph, a hydrogen flame detector is used as a detector, DB-5MS (30m × 0.25mm × 0.25.25 mu m) is used as a chromatographic column, the chromatographic operation conditions comprise that a carrier is nitrogen, the flow rate of the column is 1ml/min, the split ratio is 50:1, the injection inlet temperature is 250 ℃, the detector temperature is 250 ℃, and the injection amount is 0.2 mu L.

The characterization method of the pore structure of the catalyst is BET, instrument model: ASAP 2020M. The parameters are as follows:

Analysis Absorptive：N2 Analysis Bath Temp：77.299K

Cold Free Space：81.7371 Equilibration Interval：10s。

example 1

The method comprises the steps of taking two reactors A and B with the same specification, adding 1.3g of sesbania powder and 300g of water into the reactors A and B respectively to prepare dispersion liquid, dissolving 68.5g of copper chloride and 150.3g of zinc chloride into the water to prepare a salt solution, enabling the total concentration of copper ions and zinc ions to be 1 mol/L, adding 4.3g of 30 wt% silica sol into the prepared salt solution to prepare a mixed solution, dividing the prepared mixed solution into two parts, respectively carrying out parallel flow on the two reactors with 10 wt% of sodium carbonate solution, controlling the temperature of A to be 70 ℃, the pH value to be 7.0, and controlling the temperature of B to be 50 ℃ and the pH value to be 7.0.

After the parallel flow is finished, mixing the slurry of the A and the slurry of the B into a reactor C for aging, controlling the aging temperature to be 75 ℃ and aging for 2 h.

After the aging was complete, the slurry was filtered and washed with methanol until the wash conductivity was less than 100. mu.s/cm. Drying the washed filter cake at 110 ℃ for 10h, roasting at 280 ℃ for 8h, tabletting and forming to obtain a 4 x 4mm cylindrical (diameter 4mm, height 4mm) catalyst, namely the catalyst A.

Activating the catalyst: the catalyst A is loaded in a fixed bed hydrogenation reactor, and the loading of the catalyst is 50 ml. Firstly, the volume space velocity of nitrogen is kept for 1000h^-1Heating the reactor to 150 ℃, keeping the temperature constant for 2h to remove the physical water adsorbed by the catalyst, introducing a mixed gas with the ratio of hydrogen to nitrogen being 1:10 to perform pre-reduction for 2h, then gradually increasing the ratio of hydrogen to nitrogen to 1:5, 1:4, 1:2 and 1:1, controlling the hot spot temperature of the catalyst bed layer not to exceed 220 ℃ in the process, finally heating to 220 ℃, and reducing for 4h under the pure hydrogen atmosphere.

Example 2

Taking two reactors A and B with the same specification, adding 2.25g of microcrystalline cellulose and 300g of water respectively to prepare dispersion liquid, dissolving 110g of copper nitrate and 190.6g of zinc nitrate in water to prepare salt solution, enabling the total concentration of copper ions and zinc ions to be 1.5 mol/L, adding 4.3g of 30 wt% silica sol into the prepared salt solution to prepare mixed solution, dividing the prepared mixed solution into two parts, respectively carrying out parallel flow with 10 wt% sodium bicarbonate solution in the two reactors, controlling the temperature of A to be 65 ℃, the pH value to be 7.2, and controlling the temperature of B to be 54 ℃ and the pH value to be 7.2.

After the parallel flow is finished, mixing the slurry of the A and the slurry of the B into a reactor C for aging, controlling the aging temperature to be 70 ℃, and aging for 3 hours.

After the aging was complete, the slurry was filtered and washed with ethanol until the wash conductivity was less than 100. mu.s/cm. Drying the washed filter cake at 115 ℃ for 6h, roasting at 300 ℃ for 6h, tabletting and forming to obtain a 4 x 4mm cylindrical (diameter 4mm, height 4mm) catalyst, namely the catalyst B.

The rest of the conditions refer to example 1.

Example 3

Taking two reactors A and B with the same specification, adding 5.2g of microcrystalline cellulose and 300g of water into the reactors A and B respectively to prepare dispersion liquid, dissolving 131g of copper acetate, 176g of zinc acetate and 2.64g of sodium silicate into the water to prepare a salt solution, enabling the total concentration of copper ions and zinc ions to be 2 mol/L, dividing the prepared solution into two parts, respectively carrying out parallel flow with 15 wt% of ammonium carbonate solution in the two reactors, controlling the temperature of A to be 75 ℃, the pH value to be 7.1, and controlling the temperature of B to be 55 ℃ and the pH value to be 7.1.

After the parallel flow is finished, mixing the slurry of the A and the slurry of the B into a reactor C for aging, controlling the aging temperature to be 80 ℃, and aging for 4 hours.

After the aging was complete, the slurry was filtered and washed with ethylene glycol until the wash conductivity was less than 100 μ s/cm. Drying the washed filter cake at 105 ℃ for 12h, roasting at 320 ℃ for 4h, tabletting and forming to obtain a 4 x 4mm cylindrical (diameter 4mm, height 4mm) catalyst, namely the catalyst C.

The rest of the conditions refer to example 1.

Example 4

Taking two reactors A and B with the same specification, adding 1.3g of microcrystalline cellulose and 300g of water respectively to prepare dispersion liquid, dissolving 110g of copper nitrate, 187.6g of zinc nitrate and 5.28g of sodium silicate in water to prepare a salt solution, enabling the total concentration of copper ions and zinc ions to be 1 mol/L, dividing the prepared solution into two parts, respectively carrying out parallel flow with 20 wt% of sodium carbonate solution in the two reactors, controlling the temperature of A to be 65 ℃, the pH value to be 6.8, controlling the temperature of B to be 54 ℃ and the pH value to be 7.1.

After the aging is complete, the slurry is filtered and washed with an amount of ethanol until the wash conductivity is less than 100 μ s/cm. And drying the washed filter cake at 110 ℃ for 10h, roasting at 290 ℃ for 6h, tabletting and forming to obtain a 4 x 4mm cylindrical (diameter of 4mm and height of 4mm) catalyst, namely the catalyst D.

The rest of the conditions refer to example 1.

Example 5

Taking two reactors A and B with the same specification, adding 1.3g of microcrystalline cellulose and 300g of water respectively to prepare dispersion liquid, dissolving 116g of copper nitrate, 183g of zinc nitrate and 3.97g of sodium silicate in water to prepare a salt solution, enabling the total concentration of copper ions and zinc ions to be 2 mol/L, dividing the prepared solution into two parts, respectively carrying out parallel flow with 15 wt% of sodium carbonate solution in the two reactors, controlling the temperature of A to be 68 ℃, the pH value to be 7.0, and controlling the temperature of B to be 52 ℃ and the pH value to be 7.5.

After the parallel flow is finished, mixing the slurry of the A and the slurry of the B into a reactor C for aging, controlling the aging temperature to be 72 ℃ and aging for 3 h.

After the aging is complete, the slurry is filtered and washed with an amount of methanol until the wash conductivity is less than 100 μ s/cm. And drying the washed filter cake at 115 ℃ for 6h, roasting at 300 ℃ for 8h, tabletting and forming to obtain a 4 x 4mm cylindrical (diameter of 4mm and height of 4mm) catalyst, namely the catalyst E.

The rest of the conditions refer to example 1.

Comparative example 1

Adding dispersion of 4.5g of microcrystalline cellulose and 600g of water into a reactor, dissolving 110g of copper nitrate and 190.6g of zinc nitrate into water to prepare a salt solution, dissolving the copper nitrate and 190.6g of zinc nitrate into the water to prepare a salt solution, enabling the total concentration of copper ions and zinc ions to be 1.5 mol/L, adding 4.3g of 30 wt% of silica sol into the prepared salt solution to prepare a mixed solution, dissolving the prepared salt solution and 10 wt% of sodium carbonate into the reactor in a parallel flow mode, dropping the mixed solution into the reactor, controlling the temperature of 55 ℃ and the precipitation pH to be 7.2 in a precipitation process, aging the mixed solution at 70 ℃ for 3h after precipitation is finished, filtering the slurry, washing the slurry with ethanol until the conductivity of the washing solution is less than 100 mu s/cm to obtain a filter cake, drying the washed filter cake at 115 ℃ for 6h, roasting at 300 ℃ for 6h, and tabletting to obtain a 4 x 4mm cylindrical (diameter is 4mm and height is 4mm), thus.

The rest of the conditions refer to example 1.

Comparative example 2

The preparation was carried out as in comparative example 1, changing the precipitation temperature to 65 ℃ to obtain catalyst G.

Comparative example 3

The proportion of the same raw materials in the reactor A and the reactor B is 1:3, the same conditions as in example 1 were otherwise followed to obtain catalyst H.

Comparative example 4

The proportion of the same raw materials in the reactor A and the reactor B is 3: 1, the other conditions were the same as in example 1 to obtain catalyst I.

Comparative example 5

Catalyst J was obtained under the same conditions as in example 2, except that no silicon promoter was added.

The catalysts of examples 1-5 and comparative examples 1-5 were characterized by their BET channel parameters as given in Table 1.

TABLE 1 BET characterization of the catalyst

As shown in Table 1, the catalysts A-E obtained in the examples have similar pore channel structures and mainly consist of two pore channels of 2-5nm and 10-20nm, and the ratio of the pore volume to the total pore volume is respectively 30% -45% and 45% -55%. Comparative example catalyst F, G was prepared with only one pore channel, and the pore size of F for the low temperature reaction was larger than that of G for the high temperature reaction. H and I are also of a double-pore structure, but the number of large pores and small pores (represented by the pore volume ratio) is different due to different distribution ratios of reaction liquid. The preparation conditions of J and B are the same, except that no auxiliary agent silicon is added, so the pore channel structures are basically consistent.

Example 6

Evaluation of catalyst: the catalysts A to J prepared in examples 1 to 5 and comparative examples 1 to 5 were used for hydrogenation of n-butyraldehyde, respectively.

The hydrogenation conditions were as follows: 50ml of catalyst is filled in a reaction tube with the inner diameter of 32mm, the reaction temperature is 120 ℃, the reaction pressure (gauge pressure, the same below) is 0.5MPa, the molar ratio of the hydrogen to the aldehyde is 15:1, and the liquid hourly space velocity is 1.0ml_IBA·ml_cat ^-1·h^-1Butyraldehyde hydrogenation reaction is carried out under the condition to obtain reaction liquid, and the reaction result is detailed in a table 2.

TABLE 2 hydrogenation of n-butyraldehyde

Content%: refers to the percentage of the peak area of the corresponding product to the sum of the peak areas of the substances in the reaction solution in the gas chromatography analysis.

As is clear from Table 2, the catalyst F prepared by precipitation at a low temperature (55 ℃ C.) had a poor activity, the catalyst G prepared by precipitation at a high temperature (65 ℃ C.) had a poor selectivity, and the n-butyl n-butyrate was produced in a large amount. The catalyst H has more macropores, so that the generation amount of octanol serving as a byproduct is increased, and the specific surface area is reduced by the more macropores, so that the conversion rate is reduced. Catalyst I has a large number of pores and poor heat transfer capability, resulting in a large amount of n-butyl n-butyrate as a by-product and a high hot spot. The catalyst J, to which no silicon promoter is added, has a weak ability to decompose n-butyl n-butyrate, resulting in a large amount of n-butyl n-butyrate as a by-product.

The above examples show that the catalyst prepared by the method of the invention is used for preparing n-butyl alcohol by hydrogenation of n-butyraldehyde, and has the advantages of high catalyst activity, low hotspot temperature, high raw material conversion rate, less amount of n-butyl butyrate byproduct, good product selectivity and the like.

Claims

1. A catalyst for preparing n-butanol by hydrogenating n-butyraldehyde comprises the following components: based on the weight of the catalyst, the catalyst is added,

24-50 wt% of copper oxide; 49-75 wt% of zinc oxide; 0.5-2 wt% of silicon dioxide;

the preparation method of the catalyst comprises the following steps: according to the proportion,

(1) adding pore-forming agent aqueous dispersion into a reactor A, adding mixed solution containing copper salt, zinc salt and auxiliary agent Si and alkaline precipitator into A in a concurrent flow manner, controlling the precipitation temperature of A to be 60-80 ℃, and controlling the pH value to be 6.5-8.0;

(2) adding pore-forming agent aqueous dispersion into a reactor B, adding mixed solution containing copper salt, zinc salt and auxiliary agent Si and alkaline precipitator into the reactor B in a concurrent flow manner, controlling the precipitation temperature of the reactor B to be 45-60 ℃, and controlling the pH value to be 6.5-8.0;

(3) mixing the obtained serosity in the A and the B, and then aging for 2-4h, wherein the aging temperature is controlled to be 65-80 ℃;

(4) filtering the slurry obtained in the step (3), and washing with an organic solvent to obtain a filter cake; and drying and roasting the filter cake to obtain the catalyst.

2. The catalyst of claim 1 wherein the copper oxide is present in an amount of from 28 to 45 wt%, based on the weight of the catalyst; 54-70 wt% of zinc oxide; 0.5-2 wt% of silicon dioxide.

3. The catalyst of claim 1 wherein the copper oxide is present in an amount of 30 to 45 wt%, based on the weight of the catalyst; 54-69 wt% of zinc oxide; 0.5-2 wt% of silicon dioxide.

4. The catalyst according to claim 1, wherein the catalyst has a pore volume of 2-5nm in pore size of 20-50% of the total pore volume; the pore volume with the pore diameter of 10-20nm accounts for 40-60 percent of the total pore volume.

5. The catalyst according to claim 1, wherein the catalyst has a pore volume of 2-5nm in pore size of 30-45% of the total pore volume; the pore volume with the pore diameter of 10-20nm accounts for 45-55 percent of the total pore volume.

6. The catalyst according to claim 1, characterized in that the preparation method of the catalyst comprises the following steps: according to the proportion,

(1) adding pore-forming agent aqueous dispersion into a reactor A, adding mixed solution containing copper salt, zinc salt and auxiliary agent Si and alkaline precipitator into A in a concurrent flow manner, controlling the precipitation temperature of A to be 65-75 ℃, and controlling the pH value to be 6.8-7.5;

(2) adding pore-forming agent aqueous dispersion into a reactor B, adding mixed solution containing copper salt, zinc salt and auxiliary agent Si and alkaline precipitator into the reactor B in a concurrent flow manner, controlling the precipitation temperature of the reactor B to be 48-58 ℃, and controlling the pH value to be 6.8-7.5;

(3) mixing the obtained serosity in the A and the B, and then aging for 2-4h, and controlling the aging temperature to be 68-78 ℃;

7. The catalyst according to claim 1, wherein the copper salt is selected from one or more of copper nitrate, copper chloride, copper acetate and the like; the zinc salt is selected from one or more of zinc nitrate, zinc chloride, zinc acetate and the like; the auxiliary agent Si is selected from one or more of silica sol, sodium silicate, sodium aluminosilicate and the like.

8. The catalyst of claim 1, wherein the pore former is selected from one or more of sesbania powder, methylcellulose, and microcrystalline cellulose.

9. The catalyst of claim 1, wherein the pore-forming agent is used in an amount of 0.25 to 7.5 wt% based on the weight of the catalyst in step (1) or step (2).

10. The catalyst of claim 1, wherein the pore-forming agent is used in the amount of 0.5-5 wt% based on the weight of the catalyst in step (1) or step (2).

11. The catalyst of claim 1, wherein the pore-forming agent is used in an amount of 1-4 wt% based on the weight of the catalyst in step (1) or step (2).

12. The catalyst of claim 1, wherein the basic precipitant is one or more of sodium carbonate, potassium carbonate, sodium bicarbonate, potassium bicarbonate, sodium hydroxide, potassium hydroxide, ammonium carbonate, ammonium bicarbonate, and aqueous ammonia.

13. The catalyst as claimed in claim 1, wherein the calcination temperature of the filter cake in step (4) is 260 ℃ to 330 ℃ and the calcination time is 3-12 h.

14. The catalyst as claimed in claim 1, wherein the calcination temperature of the filter cake in step (4) is 280 ℃ to 320 ℃ and the calcination time is 4-8 h.

15. The catalyst according to claim 1, wherein the organic solvent in step (4) is one or more of methanol, ethanol and ethylene glycol; washing until the conductivity of the washing liquid is less than 100 mu s/cm.

16. The catalyst according to claim 1, wherein the pore-forming agent, the copper salt, the zinc salt and the auxiliary agent Si in step (1) and step (2) are respectively from the same raw material source and are respectively used in the same amount.