CN111659405A

CN111659405A - Method for preparing copper-based catalyst by spray drying

Info

Publication number: CN111659405A
Application number: CN202010653427.7A
Authority: CN
Inventors: 朱丽英
Original assignee: Individual
Current assignee: Individual
Priority date: 2020-07-08
Filing date: 2020-07-08
Publication date: 2020-09-15

Abstract

The invention discloses a method for preparing a copper-based catalyst by a spray drying method, which comprises the steps of preparing a suspended substance containing water and a copper-containing substance, an auxiliary agent substance and a carrier substance, then grinding the suspended substance into water-based slurry by a colloid mill, and adjusting the pH value of the water-based slurry to be alkaline. Filtering the slurry to remove mother liquor, adding a binder, adjusting the solid content of the slurry, spray-drying the slurry to obtain a catalyst precursor, and roasting to obtain the copper-based catalyst. The catalyst prepared by the method has the characteristics of uniform dispersion of active components, high activity, high selectivity, high stability and the like in high-space-velocity hydrogenation reaction.

Description

Method for preparing copper-based catalyst by spray drying

Technical Field

The invention belongs to the technical field of catalyst preparation, and particularly relates to a preparation method of a copper-based catalyst and application of the catalyst in catalytic reactions such as hydrogenation, dehydrogenation, hydrogenolysis and the like in the chemical field.

Background

The catalytic hydrogenation technology is not only widely applied to petrochemical industry and petroleum refining, but also continuously developed and applied to fine chemical industry. Designing a hydrogenation catalyst with excellent performance is one of the key technologies of catalytic hydrogenation.

In the fields of petrochemical industry and fine chemical industry, copper-based catalysts are widely applied to gas-solid phase reactions such as hydrogenation, dehydrogenation and reforming hydrogen production, for example, the reactions of methyl formate preparation by methanol dehydrogenation, methanol preparation by medium-low pressure synthesis gas, hydrogen production by methanol steam reforming, carbon monoxide low-temperature shift and the like. The main components of conventional copper-based catalyst products are typically CuO, ZnO and Al₂O₃Mainly comprises three metal components of Cu, Zn and AlThe nitrate and alkali liquor are subjected to coprecipitation reaction to synthesize the nitrate. For example, patent CN102755897A discloses a copper-based catalyst prepared by distributed precipitation-spray drying, which is prepared by performing co-current co-precipitation reaction on nitrates of Cu, Zn and Al and a sodium carbonate solution under certain temperature and pH conditions, and performing washing, drying, roasting and other steps.

After the microstructure of the traditional copper-based catalyst is researched, the crystal form of the copper-based catalyst prepared by a coprecipitation method is in a random state, the particle size distribution and the pore size distribution of CuO microcrystals are very uneven, and the specific surface area of the catalyst is small, so that the catalytic activity, particularly the selectivity and the thermal stability of a target product of the copper-based catalyst are relatively low, and the service life of the catalyst is relatively short.

Therefore, there is a need to provide a hydrogenation catalyst with short preparation process, high hydrogenation conversion rate, high hydrogenation selectivity and low cost.

Disclosure of Invention

The invention aims to provide a preparation method for preparing a copper-based catalyst by using spray drying. Compared with the catalyst prepared by the traditional method, the catalyst prepared by the method has the advantages that the distribution of CuO active components is more uniform, and the activity is higher under the condition of high space velocity. The catalyst produced by the method greatly shortens the process flow, thereby reducing the production cost.

In order to achieve the purpose, the invention adopts the following technical scheme.

A method for preparing a copper-based catalyst by spray drying comprises the following steps:

(a) preparing a water-based slurry comprising water, a copper-containing substance, an auxiliary substance, a carrier substance and a binder;

(b) adjusting the pH of the slurry to obtain an insoluble compound slurry;

(c) filtering the slurry to remove most of the mother liquor, adding deionized water and a binder, stirring and pulping;

(d) spray drying the slurry to obtain a catalyst precursor;

(e) and calcining the catalyst precursor to prepare the copper-based catalyst.

In the method of the present invention, the copper-containing substance in step 1 includes copper nitrate, basic copper carbonate, copper chloride, copper ammonia solution, copper hydroxide, copper oxide or cuprous oxide, preferably copper nitrate or copper chloride. The auxiliary substances comprise zinc chloride, zinc acetate, manganese nitrate, manganese acetate, zirconium hydroxide or zirconium acetate, and preferably one or more of zinc acetate, manganese nitrate and zirconium acetate; the carrier material comprises kaolin, diatomite, clay, alumina, silicon dioxide, calcium silicate, magnesium silicate or silicon-aluminum molecular sieve, preferably one or more of diatomite, silicon dioxide, alumina or magnesium silicate.

In the process of the invention, step 1 relates to the preparation of a slurry, the copper-containing material, the auxiliary agent-containing material and water being initially brought into suspension. This suspension may be milled until the desired particle size is formed in the slurry. Furthermore, the copper-containing material, the auxiliary agent-containing material and the carrier may be milled separately or together until the desired particle size is achieved, before the suspension is formed.

In the process of the present invention, the average particle size formed in the slurry of step 1 is from 0.1 microns to 20 microns, preferably from 0.2 to 10 microns, more preferably from 0.5 to 5 microns. More desirably, the particle size and size distribution are achieved, and the milling time may be as short as about 10 to 30 minutes, or 1 to 5 hours.

In the process of the present invention, the alkaline solution for adjusting the pH in step 2 is an aqueous solution of ammonia, sodium hydroxide, potassium hydroxide, sodium carbonate or sodium bicarbonate, preferably an aqueous solution of sodium carbonate.

In the method, the pH value of the slurry obtained in the step 2 is preferably adjusted within a range of 6.5-9.0, and more preferably within a range of 7.0-8.5.

In the method of the present invention, step 3 filters the formed slurry of insoluble compounds to remove most of the mother liquor, and adds deionized water and a binder to the filter cake for re-pulping.

In the method of the present invention, the binder in step 3 includes silica gel, aluminum gel, water glass, aluminum chloride, methyl cellulose, polyvinyl alcohol, sesbania powder or starch, and preferably one or more of aluminum gel, water glass and aluminum chloride. The amount of the binder added is 1.0wt% to 30.0wt%, and the specific addition amount is determined according to the solid content in the suspension.

In the method of the present invention, the slurry prepared in step 1 is spray-dried using a centrifugal spray dryer or a pressure type spray dryer in step 3. The resulting powder has an average particle diameter of 10 to 90 microns, preferably 40 to 70 microns.

In the method of the present invention, step 4 is to calcine the powder obtained in step 3 at a temperature of 250 ℃ to 600 ℃, preferably 360 ℃ to 580 ℃, to form a powdery copper-based catalyst.

Fig. 1 is a transmission electron microscope (HRTEM) of a copper-based catalyst, wherein a is the catalyst prepared in comparative example 1, and B is the catalyst prepared in example 3, it can be seen that CuO particles having particle sizes of 15 to 20nm are distributed relatively in a matrix of a carrier, CuO is a catalyst prepared by the present invention alone in a more uniform dispersion state, and the particle size of CuO particles is smaller.

The copper-based catalysts according to the invention can be suitable for hydrogenation, hydrogenolysis or dehydrogenation reactions. Possible reactions include: hydrogenolysis of lipids, hydrogenation of nitriles (e.g. 3-hydroxypropionitrile), dehydrogenation of primary alcohols to aldehydes, dehydrogenation of secondary alcohols to ketones, dehydrogenation of diols (e.g. butanediol), hydrogenation of aldehydes, hydrogenation of nitroaromatics, hydrogenation of ketones or hydrogenation of furfural.

In a preferred embodiment, the copper-based catalyst prepared by the process according to the invention is used for the hydrogenation of carbonyl compounds, in particular for the hydrogenation of aldehydes, ketones, carboxylic acids and esters or diesters thereof. The hydrogenation of dimethyl 1, 4-cyclohexanedicarboxylate (DMCD) to produce 1, 4-Cyclohexanedimethanol (CHDM) using the above-described catalyst is particularly preferred.

Drawings

FIG. 1 shows HRTEM of a copper-based catalyst (A is comparative example 1 and B is example 3).

Detailed Description

The invention is further illustrated by the following examples and comparative examples. These specific examples are not intended to limit the scope of the invention in any way.

Example 1

Accurate weighing of CuCl₂·2H₂Adding deionized water into the solution O, stirring the solution O to dissolve the solution O to prepare solution A, and enabling the solution A to contain Cu²⁺The ion concentration was 0.5 mol/L. Accurate weighing C₄H₆O₄Zn·2H₂Adding deionized water into O, stirring to dissolve to obtain solution B, and dissolving Zn in the solution B² ⁺The ion concentration was 0.5 mol/L. 0.45 mol/L potassium hydroxide solution is prepared. Weighing the required solution A and solution B according to the mass percent of Cu and Zn in the final catalyst, adding the solution A and the solution B into a reaction kettle, then adding a diatomite carrier into the reaction kettle, dropwise adding a potassium hydroxide solution, strongly stirring, and controlling the reaction temperature to be 30 DEG^oAnd C, adjusting the pH to 7.8-8.0, and treating by using a colloid mill to obtain slurry containing insoluble compounds. Most of mother liquor is removed from the insoluble slurry by centrifugal filtration, 3wt% of alumina gel and deionized water are added into the filter cake and fully stirred, and the solid content of the slurry is adjusted to 25%. The slurry is passed through a centrifugal spray dryer with the feed inlet temperature being controlled 380^oC, discharge port temperature 150^oC, obtaining a catalyst precursor, and then obtaining a catalyst precursor at 450^oAnd C, roasting for 9 hours to obtain a catalyst finished product. In the catalyst, the mass percent of Cu is 45.63%, the mass percent of Zn is 5.17%, and the specific surface area of the catalyst is 150.5 m²Per g, Cu metal surface area in catalyst 18.5 m²The physical properties are shown in Table 1.

Example 2

Accurately weigh Cu (NO)₃)₂·3H₂Adding deionized water into the solution O, stirring the solution O to dissolve the solution O to prepare solution A, and enabling the solution A to contain Cu²⁺The ion concentration was 0.8 mol/L. Accurate weighing C₄H₆O₄Zn·2H₂Adding deionized water into O, stirring to dissolve to obtain solution B, and dissolving Zn in the solution B²⁺The ion concentration was 0.5 mol/L. Preparing 0.45 mol/L sodium carbonate solution. Weighing the required solution A and solution B according to the mass percent of Cu and Zn in the final catalyst, adding the solution A and the solution B into a reaction kettle, then adding a diatomite carrier into the reaction kettle, and drippingAdding sodium carbonate solution and stirring intensively, controlling the reaction temperature to be 30 DEG^oAnd C, adjusting the pH to 7.8-8.0, and treating by using a colloid mill to obtain slurry containing insoluble compounds. Centrifuging the insoluble slurry, filtering most of mother liquor, adding 3wt% of silica gel and deionized water into the filter cake, and fully stirring to adjust the solid content of the slurry to 25%. The slurry is passed through a centrifugal spray dryer with the feed inlet temperature being controlled 380^oC, discharge port temperature 150^oC, obtaining a catalyst precursor, and then obtaining a catalyst precursor at 450^oAnd C, roasting for 9 hours to obtain a catalyst finished product. The mass percentage of Cu in the catalyst is 44.89 percent, the mass percentage of Zn is 5.05 percent, and the specific surface area of the catalyst is 108.7 m²Per g, Cu metal surface area in catalyst 18.3 m²The physical properties are shown in Table 1.

Example 3

Accurately weigh Cu (NO)₃)₂·3H₂Adding deionized water into the solution O, stirring the solution O to dissolve the solution O to prepare solution A, and enabling the solution A to contain Cu²⁺The ion concentration was 0.8 mol/L. Accurate weighing (CH)₃COO)₃Mn·2H₂Adding deionized water into O, stirring and dissolving to prepare solution B, and enabling Mn in solution B to be²⁺The ion concentration was 0.8 mol/L. Preparing 0.45 mol/L sodium carbonate solution. Weighing the required solution A and solution B according to the mass percent of Cu and Mn in the final catalyst, adding the solution A and the solution B into a reaction kettle, then adding a silicon oxide carrier into the reaction kettle, dropwise adding a sodium carbonate solution and strongly stirring, and controlling the reaction temperature to be 30 DEG^oAnd C, adjusting the pH to 8.0-8.2, and treating by using a colloid mill to obtain slurry containing insoluble compounds. Centrifuging the insoluble slurry, filtering most of mother liquor, adding 3wt% of water glass and deionized water into the filter cake, and fully stirring to adjust the solid content of the slurry to 25%. The slurry is passed through a centrifugal spray dryer with the feed inlet temperature being controlled 380^oC, discharge port temperature 150^oC, obtaining a catalyst precursor, and then obtaining a catalyst precursor at 450^oAnd C, roasting for 9 hours to obtain a catalyst finished product. The mass percent of Cu in the catalyst is 43.25 percent, the mass percent of Mn is 4.98 percent, and the specific surface area of the catalyst is 207.5 m²In terms of a/g ratio, the Cu metal surface area in the catalyst was 17.6 m²/g，The physical properties are detailed in Table 1.

Example 4

Accurate weighing (CH)₃COO)₃Mn·2H₂Adding deionized water into the solution O, stirring and dissolving the mixture to prepare solution A, and enabling Mn in the solution A to be²⁺The ion concentration was 0.5 mol/L. 0.45 mol/L potassium hydroxide solution is prepared. Weighing the required solid Cu (OH) in terms of mass percent of Cu and Mn in the final catalyst₂Adding the solution A into a reaction kettle, then adding a magnesium silicate carrier into the reaction kettle, dropwise adding a potassium hydroxide solution, strongly stirring, and controlling the reaction temperature to be 30 DEG^oAnd C, adjusting the pH to 8.0-8.2, and treating by using a colloid mill to obtain slurry containing insoluble compounds. Centrifuging the insoluble slurry, filtering most of mother liquor, adding 3wt% of aluminum chloride and deionized water into the filter cake, and fully stirring to adjust the solid content of the slurry to 25%. Passing the slurry after colloid milling through a centrifugal spray dryer, and controlling the temperature of a feed inlet 380^oC, discharge port temperature 150^oC, obtaining a catalyst precursor, and then obtaining a catalyst precursor at 450^oAnd C, roasting for 9 hours to obtain a catalyst finished product. The mass percent of Cu in the catalyst is 46.02%, the mass percent of Mn in the catalyst is 5.21%, and the specific surface area of the catalyst is 187.7 m²Per g, Cu metal surface area in catalyst 15.8 m²The physical properties are shown in Table 1.

Example 5

Accurate weighing of CuCl₂·2H₂Adding deionized water into the solution O, stirring the solution O to dissolve the solution O to prepare solution A, and enabling the solution A to contain Cu²⁺The ion concentration was 0.8 mol/L. Accurate weighing C₈H₁₂O₈Adding Zr into deionized water, stirring and dissolving to prepare solution B, and leading Zr in the solution B⁴⁺The ion concentration was 0.8 mol/L. 0.45 mol/L potassium hydroxide solution is prepared. Weighing the required solution A and solution B according to the mass percent of Cu and Zr in the final catalyst, adding the solution A and the solution B into a reaction kettle, then adding a silicon oxide carrier into the reaction kettle, dropwise adding a potassium hydroxide solution, strongly stirring, and controlling the reaction temperature to be 30 DEG^oAnd C, treating the mixture with a colloid mill to obtain slurry containing insoluble compounds, wherein the pH value of the mixture is 8.0-8.2. Centrifuging the insoluble slurry and filtering to remove most of the mother liquorAdding 3wt% of silica gel and deionized water into the filter cake, fully stirring, and adjusting the solid content of the slurry to 25%. The slurry is passed through a centrifugal spray dryer with the feed inlet temperature being controlled 380^oC, discharge port temperature 150^oC, obtaining a catalyst precursor, and then obtaining a catalyst precursor at 450^oAnd C, roasting for 9 hours to obtain a catalyst finished product. In the catalyst, the mass percent of Cu is 50.81%, the mass percent of Zr is 5.16%, and the specific surface area of the catalyst is 305.5 m²Per g, Cu metal surface area in catalyst 19.8 m²The physical properties are shown in Table 1.

Example 6

Accurately weigh Cu (NO)₃)₂·3H₂Adding deionized water into the solution O, stirring the solution O to dissolve the solution O to prepare solution A, and enabling the solution A to contain Cu²⁺The ion concentration was 0.7 mol/L. Accurate weighing C₈H₁₂O₈Adding Zr into deionized water, stirring and dissolving to prepare solution B, and leading Zr in the solution B⁴⁺The ion concentration was 0.7 mol/L. 0.45 mol/L sodium bicarbonate solution is prepared. Weighing the required solution A and solution B according to the mass percent of Cu and Zr in the final catalyst, adding the solution A and the solution B into a reaction kettle, then adding an alumina carrier into the reaction kettle, dropwise adding a sodium bicarbonate solution, strongly stirring, and controlling the reaction temperature to be 30 DEG^oAnd C, the pH value is 8.5-8.7, and the slurry containing the insoluble compound is obtained after the colloid mill treatment. Centrifuging the insoluble slurry, filtering most of mother liquor, adding 3wt% of alumina gel and deionized water into the filter cake, and fully stirring to adjust the solid content of the slurry to 25%. The slurry is passed through a centrifugal spray dryer with the feed inlet temperature being controlled 380^oC, discharge port temperature 150^oC, obtaining a catalyst precursor, and then obtaining a catalyst precursor at 450^oAnd C, roasting for 9 hours to obtain a catalyst finished product. In the catalyst, the mass percent of Cu is 45.27%, the mass percent of Zr is 5.01%, and the specific surface area of the catalyst is 380.7 m²Per g, Cu metal surface area in catalyst 20.8 m²The physical properties are shown in Table 1.

Comparative example 1

Accurately weigh Cu (NO)₃)₂·3H₂Adding deionized water, stirring and dissolving to prepare solutionA, making Cu in²⁺The ion concentration was 0.7 mol/L. 0.45 mol/L sodium bicarbonate solution is prepared. Weighing the required solution A according to the mass percent of Cu in the final catalyst, adding the solution A into a reaction kettle, then adding an alumina carrier into the reaction kettle, dropwise adding a sodium bicarbonate solution, strongly stirring, and controlling the reaction temperature to be 30 DEG^oAnd C, treating the mixture with a colloid mill to obtain slurry containing insoluble compounds, wherein the pH value of the slurry is 7.8-8.0. Centrifuging the insoluble slurry, filtering most of mother liquor, adding deionized water into a filter cake, fully stirring, and adjusting the solid content of the slurry to 25%. The slurry is passed through a centrifugal spray dryer with the feed inlet temperature being controlled 380^oC, discharge port temperature 150^oC, obtaining a catalyst precursor, and then obtaining a catalyst precursor at 450^oAnd C, roasting for 9 hours to obtain a catalyst finished product. The Cu content of the catalyst is 44.82% by mass, and the specific surface area of the catalyst is 80.9 m²Per g, Cu metal surface area in catalyst 6.5 m²The physical properties are shown in Table 1.

Determination of Cu Metal surface area

By N₂Principle of O decomposition (N)₂O pulse chemisorption) Cu metal area of the catalyst:

2Cu+N₂O→Cu₂O+N₂

for this purpose, 230 ℃ is measured in a chemisorption apparatus (Micromeritics AutoChem II 2920)^oMixed hydrogen (5% H in Ar) at C₂Synthesis gas of (c) for 8 hours, purge with Ar and start N₂And O pulse chemical adsorption. N formed in Ar as determined by TCD Detector₂The Cu metal surface area is measured and calculated.

Table 1 catalyst components and associated physical properties.

Activity test for the hydrogenation of dimethyl 1, 4-cyclohexanedicarboxylate (DMCD) to 1, 4-Cyclohexanedimethanol (CHDM).

The hydrogenation reaction is carried out on a high-pressure micro-reaction catalyst evaluation device for preventing heatThe effect has an influence on the catalyst performance, and 3.0g (crushed into 20-40 meshes after tabletting) of the catalyst and quartz sand (40-60 meshes) are mixed according to the mass ratio of 1:1 and are filled into a reactor. At 10% H₂/N₂Under an atmosphere of 5^oHeating to 250 ℃ at a speed of C/min^oCAnd keeping the temperature for 2 hours to fully reduce and activate the catalyst. The temperature of the bed layer is reduced to 240 DEG^oC, raising the hydrogen pressure to 8MPa, and keeping H₂The ratio of DMCD is 406, and the liquid phase space velocity is 0.5-2.0 h^-1. The content of the reaction product was analyzed by Agilent GC7890A gas chromatography, column HP-5, hydrogen flame ionization detector, and the amount of sample was 0.2. mu.l. Calculating the DMCD conversion rate and the CHDM selectivity of the target product according to the chromatographic analysis result.

Table 2 comparison of the performance of the catalysts in the gas phase hydrogenation of DMCD.

From the results in table 2, it is clear that the conversion and selectivity of the catalysts of each group of examples can reach about 99% compared to the comparative examples. The space velocity of the liquid phase thus directly reflects the catalytic activity, in particular the activity of the catalyst = space velocity of the liquid phase/conversion/selectivity. According to settlement results, the catalyst prepared by the invention can still keep higher activity at high space velocity, and can reach more than 2.8g/gcat.

In addition, the catalyst prepared using the comparative example technique was slightly less active in the gas phase hydrogenation of DMCD, approximately 2.4 g/gcat.h.

From the data, the embodiments of the present invention achieve the technical effects of high hydrogenation conversion rate, high selectivity, etc. under high space velocity conditions. Meanwhile, the copper-based catalyst provided by the invention also has higher dehydrogenation efficiency in catalytic dehydrogenation reaction.

The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes of the method described according to the present invention may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention shall fall within the protection scope of the present invention.

Claims

1. A method for preparing a copper-based catalyst by spray drying, the method comprising the steps of:

(a) preparing water-based slurry containing water, copper-containing substance, auxiliary substance and carrier substance;

(b) adjusting the pH of the slurry to obtain an insoluble compound slurry;

(d) spray drying the slurry to obtain a catalyst precursor;

(e) and calcining the catalyst precursor to prepare the copper-based catalyst.

2. The method of claim 1, wherein the copper-containing substance comprises one or more of copper nitrate, basic copper carbonate, copper chloride, copper ammonia solution, copper hydroxide, copper oxide or cuprous oxide.

3. The method of claim 1 wherein the adjunct material comprises one or more of zinc chloride, zinc acetate, manganese nitrate, manganese acetate, zirconium hydroxide or zirconium acetate.

4. The method of claim 1, wherein the carrier material comprises one or more of kaolin, diatomaceous earth, clay, alumina, silica, calcium silicate, magnesium silicate, or aluminosilicate molecular sieves.

5. The method of claim 1, wherein the binder comprises one or more of silica gel, aluminum gel, water glass, aluminum chloride, methyl cellulose, polyvinyl alcohol, sesbania powder, or starch.

6. The method of claim 1, wherein the pH of the slurry is adjusted in the range of preferably 6.5 to 9.0, more preferably 7.0 to 8.5.

7. The process of claim 1, wherein the catalyst is a hydrogenation, hydrogenolysis or dehydrogenation catalyst.