Copper oxide having high specific surface area, small crystallite size and low chlorine impurity content

Abstract

The present invention relates to a copper oxide powder having a specific surface area of at least 25.0 m 2 / g to 70.0 m 2 / g, a crystallite size of not more than 150.0 Angstrom (A), and a chlorine content of less than 200 ppm, and a process for the production of the copper oxide powder.

Description

Technical Field

[0001] This invention relates to a copper oxide powder with high specific surface area, small grain size, and low chlorine impurity content, particularly suitable for use in catalysts for the hydrogenation of wax esters to alcohols. The invention also relates to a method for preparing copper oxide powder with high specific surface area, small grain size, and low chlorine impurity content. Background Technology

[0002] Copper oxide (CuO) is an important transition metal oxide with wide applications in catalysis. For example, copper oxide is commonly used as the catalytically active component in catalysts for the hydrogenation of fatty acid wax esters to alcohols and the hydrogenation of CO2 to methanol.

[0003] Copper oxide powder can be prepared by various methods, among which the most commonly used method on an industrial scale is to produce copper oxide by calcining and decomposing basic copper carbonate. Basic copper carbonate as a raw material can be prepared, for example, by reacting a soluble copper salt (e.g., copper sulfate or copper nitrate) with a precipitant (e.g., sodium carbonate or sodium bicarbonate) under appropriate temperature conditions, followed by washing and calcination to decompose and form copper oxide.

[0004] However, as described in Chinese patent application CN106745179A, the method for preparing copper oxide by calcining and decomposing basic copper carbonate suffers from high impurities in the copper source, making the resulting copper oxide powder unsuitable for applications requiring high purity. To overcome these shortcomings, this patent application proposes a method for preparing electronic-grade high-purity copper oxide, comprising: using metallic copper as raw material, preparing a copper-ammonia complex solution via ammonia leaching, obtaining basic copper carbonate through deammoniation and filtration, and then calcining to obtain electronic-grade high-purity copper oxide.

[0005] Chinese patent application CN104445360A also mentions that the production of high-purity active copper oxide powder usually adopts the carbonate calcination method. However, the product obtained by the carbonate calcination method has disadvantages such as low purity, poor dispersibility, and low product activity due to coarsening of the grains after calcination. In order to overcome the disadvantages of the copper oxide powder, this patent application proposes a method for preparing high-purity active copper oxide powder by spray pyrolysis of copper ammonia solution.

[0006] Despite the aforementioned drawbacks of basic copper carbonate or carbonate calcination, this method remains highly important in industrial practice due to its relatively simple process and the ease with which safety and operational requirements of the equipment can be met.

[0007] Furthermore, the copper oxide powder currently available on the market does not exhibit satisfactory catalytic activity in the wax ester hydrogenation process. Summary of the Invention

[0008] One of the objectives of this invention is to provide a copper oxide powder that exhibits satisfactory catalytic activity in the hydrogenation process of wax esters.

[0009] This objective is achieved using a copper oxide powder with high specific surface area, small grain size, and low chlorine impurity content.

[0010] Another object of the present invention is to provide a method for preparing copper oxide powder with high specific surface area, small grain size and low chlorine impurity content by calcining basic copper carbonate.

[0011] This objective is achieved through the design of process steps and control of process conditions in the preparation of basic copper carbonate.

[0012] Accordingly, in a first aspect, the present invention provides a copper oxide powder having a 25.0 μm... 2 / g to 70.0m 2 The specific surface area per g, the grain size not exceeding 150.0 Å, and the chlorine content less than 200 ppm.

[0013] In a second aspect, the present invention provides a method for preparing copper oxide powder, comprising the steps of: (1) An aqueous solution of a water-soluble copper salt and an aqueous solution of a water-soluble alkali metal carbonate are added to a precipitation reactor containing an aqueous solvent at a constant temperature in the range of 20°C to 70°C at a constant flow rate. The addition rate of the aqueous solution of the water-soluble alkali metal carbonate is controlled to maintain the pH of the system in the range of 6.0 to 9.0 and keep the pH constant. The reaction is carried out under stirring to obtain a slurry containing a precipitate. The water-soluble copper salt and the water-soluble alkali metal carbonate are used in a molar ratio in the range of 0.7 to 1.0, where the molar ratio is expressed as Cu... 2+ CO3 2- count; (2) Allow the slurry to age for 20 to 90 minutes; (3) Filter the precipitate from the slurry and wash it with deionized water; (4) The precipitate is dried and then calcined in air at a temperature in the range of 200°C to 400°C for at least 0.5 hours to obtain copper oxide powder.

[0014] In a third aspect, the present invention provides a precursor composition for a catalyst for the hydrogenation of wax esters to alcohols, comprising: (A) Copper oxide powder as described in the first aspect of this document or copper oxide powder obtained by the method described in the second aspect of this document. (B) Carrier; and (C) Optionally, a co-catalytic or co-catalytic component.

[0015] In a fourth aspect, the present invention provides a catalyst for the hydrogenation of wax esters to alcohols, which is obtained by molding and calcining a precursor composition of the catalyst for the hydrogenation of wax esters to alcohols as described in the third aspect.

[0016] Compared with conventional copper oxide powder, the copper oxide powder according to the present invention, or the copper oxide powder prepared by the method according to the present invention, improves the catalytic activity of the catalyst for the hydrogenation of wax esters to alcohols and increases the conversion rate of the hydrogenation of wax esters to alcohols. Detailed Implementation

[0017] In this document, the term "grain size," also known as grain size, has the meaning known in the art. Specifically, the grain size of copper oxide refers to the statistical average size of individual grains in a polycrystalline structure of copper oxide, determined by X-ray powder diffraction (XRD).

[0018] In this paper, the term "wax ester" refers to an ester having a long-chain fatty acid structural moiety and a long-chain fatty alcohol structural moiety, typically having a total number of carbon atoms of 30 or more; for example, the chain length of the long-chain fatty acid structural moiety may be C12 to C36, and the chain length of the long-chain fatty alcohol structural moiety may be C16 to C36.

[0019] In this paper, the term "specific surface area" refers to the total accessible surface area per unit mass of solid material, calculated by analyzing the physical adsorption isotherms of gases based on the Brunauer–Emmett–Teller (BET) theory, and is expressed in m² / g.

[0020] In this paper, the term "chlorine content" refers to the impurity chlorine content in copper oxide powder, determined by argentometric titration, in ppm by weight.

[0021] In a first aspect, the present invention provides a copper oxide powder having a particle size of 25.0 μm. 2 / g to 70.0 m 2 The specific surface area per g, the grain size not exceeding 150.0 Å, and the chlorine content less than 200 ppm.

[0022] Preferably, the copper oxide powder according to the present invention has a particle size of 40.0 μm. 2 / g to 60.0 m 2 / g, especially 45.0 m 2 / g to 60.0 m 2 Specific surface area per g.

[0023] Preferably, the copper oxide powder according to the invention has a grain size of no more than 140.0 Å, particularly no more than 135.0 Å.

[0024] Preferably, the copper oxide powder according to the invention has a chlorine content of no more than 180 ppm, particularly no more than 170 ppm.

[0025] The copper oxide powder according to the present invention can have a D in the range of 1.0 micrometer to 10.0 micrometer. 10 D in the range of 3.0 micrometers to 25.0 micrometers 50 and D in the range of 5.0 micrometers to 100.0 micrometers. 90 Preferably, the copper oxide powder according to the present invention can have a D in the range of 1.0 micrometer to 2.0 micrometer. 10 D in the range of 3.0 micrometers to 20.0 micrometers 50 and D in the range of 5.0 micrometers to 50.0 micrometers 90 .

[0026] The copper oxide powder according to the present invention can be prepared by means of the method described herein.

[0027] In a second aspect, the present invention provides a method for preparing copper oxide powder, comprising the steps of: (1) An aqueous solution of a water-soluble copper salt and an aqueous solution of a water-soluble alkali metal carbonate are added to a precipitation reactor containing an aqueous solvent at a constant temperature in the range of 20°C to 70°C at a constant flow rate. The addition rate of the aqueous solution of the water-soluble alkali metal carbonate is controlled to maintain the pH of the system in the range of 6.0 to 9.0 and keep the pH constant. The reaction is carried out under stirring to obtain a slurry containing a precipitate. The water-soluble copper salt and the water-soluble alkali metal carbonate are used in a molar ratio in the range of 0.7 to 1.0, where the molar ratio is expressed as Cu... 2+ CO3 2- count; (2) Allow the slurry to age for 20 to 90 minutes; (3) Filter the precipitate from the slurry and wash it with deionized water; (4) The precipitate is dried and then calcined in air at a temperature in the range of 200°C to 400°C for at least 0.5 hours to obtain copper oxide powder.

[0028] The method of the present invention does not particularly limit the precipitation reactor, and any type of reactor suitable for precipitation reaction known in the art can be used.

[0029] In step (1) (i.e., the precipitation step), the water-soluble copper salt reacts with the water-soluble alkali metal carbonate in an aqueous solution (hereinafter referred to as the precipitation reaction) to generate a precipitate including basic copper carbonate (Cu2(OH)2CO3). More specifically, the precipitate may include basic copper carbonate (Cu2(OH)2CO3) and copper hydroxide (Cu2(OH)2CO3). (OH)2).

[0030] The water-soluble copper salt is one or more of those known to those skilled in the art, such as one selected from the group consisting of, preferably, copper nitrate or its hydrate, copper sulfate or its hydrate, and copper chloride or its hydrate.

[0031] The water-soluble alkali metal carbonate is one or more of those known to those skilled in the art, such as sodium carbonate or its hydrate, potassium carbonate or its hydrate, preferably sodium carbonate or its hydrate.

[0032] Taking copper nitrate and sodium carbonate as examples, the following reaction occurs between water-soluble copper salts and water-soluble alkali metal carbonates, forming a precipitate:

[0033] In step (1), the precipitation reaction can be carried out at room temperature or at a higher constant temperature, for example, at a constant temperature in the range of 20°C to 70°C, more preferably at a constant temperature in the range of 40°C to 55°C. Those skilled in the art will understand that the constant temperature allows the temperature to vary within ±1°C, preferably ±0.5°C, of ​​the specified value.

[0034] The aqueous solution of the water-soluble copper salt can be added to the precipitation reactor at a constant flow rate. Simultaneously with the addition of the aqueous solution of the water-soluble copper salt, an aqueous solution of a water-soluble alkali metal carbonate is added to the reactor at a controlled rate to maintain the pH of the system constant within the range of 6.0 to 9.0, preferably within the range of 7.0 to 8.0. More preferably, the pH of the system is maintained constant within the range of 7.1 to 7.5. Those skilled in the art will understand that this constant pH allows for pH variations within ±0.2 of a specified value.

[0035] The water-soluble copper salt and the water-soluble alkali metal carbonate are used in a molar ratio of 0.7 to 1.0, preferably 0.8 to 0.9, wherein the molar ratio is expressed as Cu 2+ CO3 2- The concentration of the aqueous solution of the water-soluble copper salt is preferably 1.0 to 5.0 mol / L, more preferably 3.0 to 5.0 mol / L, in order to obtain Cu. 2+ The concentration of the aqueous solution of the water-soluble alkali metal carbonate is 1.0 to 5.0 mol / L, preferably 1.5 to 3.0 mol / L, calculated as Na2CO3.

[0036] Deionized water is preferred as the aqueous solvent, and more preferably deionized water with a conductivity of less than 1 µS / cm. The amount of the aqueous solvent is preferably 3 to 5 times the amount of copper (calculated as Cu) in the water-soluble copper salt to be added, by weight.

[0037] Preferably, the addition rates of the aqueous solutions of the water-soluble copper salt and the water-soluble alkali metal carbonate are controlled so that the precipitation reaction proceeds for 30 to 120 minutes, more preferably 60 to 90 minutes.

[0038] In step (2), the slurry containing precipitates obtained in step (1) is aged for 20 to 90 minutes, preferably 40 to 60 minutes. The aging is carried out under static conditions, preferably in the sedimentation reactor. Preferably, the aging is carried out at a temperature in the range of 20°C to 70°C, more preferably in the range of 40°C to 55°C.

[0039] In step (3), the precipitate is filtered out from the slurry and washed with deionized water. Specifically, the aged slurry containing the precipitate can be transferred to a filtration device for filtration. The filtration can be carried out using any known method and filtration device.

[0040] The filtered precipitate (i.e., filter cake) is washed with deionized water. Preferably, deionized water is used for washing until the conductivity of the washing solution is below 300 µS / cm. In particular, deionized water in the temperature range of 20°C to 30°C can be used.

[0041] In step (4), the precipitate is dried and then calcined in an air atmosphere to obtain copper oxide powder.

[0042] The drying can be carried out at a temperature of 100°C to 160°C, for example 130°C to 150°C, in any drying apparatus; preferably, it is carried out until the moisture content is less than 0.5% by weight.

[0043] After drying, the precipitate is transferred to a calcining apparatus. The method according to the invention does not place particular requirements on the calcining apparatus; any known type of calcining furnace, such as a rotary calcining furnace, can be used.

[0044] The calcination is carried out at a temperature ranging from 200°C to 400°C, preferably from 280°C to 400°C, and more preferably from 280°C to 300°C. The calcination can last for at least 0.5 hours, preferably from 0.5 hours to 1 hour. Through calcination, basic copper carbonate and copper hydroxide decompose into copper oxide.

[0045] Optionally, the method according to the invention may include a step of classifying the copper oxide powder by particle size after step (4). Depending on the needs of the application, the copper oxide powder may be processed by any suitable particle size classification method to obtain copper oxide powder with the desired particle size distribution.

[0046] The copper oxide powder prepared according to the method of the present invention has a particle size of at least 25.0 μm. 2 / g to 70.0 m 2Specific surface area per g, grain size not exceeding 150 Å, and chlorine content below 200 ppm.

[0047] Preferably, the copper oxide powder prepared according to the method of the present invention has a particle size of 40.0 μm. 2 / g to 60.0 m 2 / g, especially 45.0 m 2 / g to 60.0 m 2 Specific surface area per g.

[0048] Preferably, the copper oxide powder prepared according to the method of the present invention has a grain size of no more than 140.0 Å, particularly no more than 135.0 Å.

[0049] Preferably, the copper oxide powder prepared according to the method of the present invention has a chlorine content of not more than 180 ppm, particularly not more than 170 ppm.

[0050] The copper oxide powder prepared by the method according to the present invention can have a Do in the range of 1.0 μm to 10.0 μm. 10 D in the range of 3.0 micrometers to 25.0 micrometers 50 and D in the range of 5.0 micrometers to 100.0 micrometers. 90 Preferably, the copper oxide powder according to the present invention can have a D in the range of 1.0 micrometer to 2.0 micrometer. 10 D in the range of 3.0 micrometers to 20.0 micrometers 50 and D in the range of 5.0 micrometers to 50.0 micrometers 90 .

[0051] The inventors of this invention have discovered that, compared with conventional copper oxide powder, the copper oxide powder according to the present invention or the copper oxide powder prepared by the method according to the present invention improves the catalytic activity of the catalyst for the hydrogenation of wax esters to alcohols and increases the conversion rate of the hydrogenation of wax esters to alcohols.

[0052] Therefore, in a third aspect, the present invention provides a precursor composition for a catalyst for the hydrogenation of wax esters to alcohols, comprising: (A) Copper oxide powder as described in the first aspect of this document or copper oxide powder obtained by the method described in the second aspect of this document, (B) Carrier; and (C) Optionally, a co-catalytic component or a co-catalytic component.

[0053] In the precursor composition, the amount of component (A) (i.e., copper oxide powder as described in the first aspect of this document or copper oxide powder obtained by the method described in the second aspect of this document) may be from about 50% by weight to 75% by weight; the amount of component (B) (i.e., the carrier) may be from 10% by weight to 40% by weight; and the amount of component (C) may be no more than 30% by weight, based on the total amount of the precursor composition.

[0054] The support may be selected from siliceous supports. Examples of siliceous supports include, but are not limited to, silica, metal silicates or oxides thereof, such as Group II and Group III metal silicates or oxides thereof, such as clay, especially bentonite.

[0055] Materials that can be used as co-catalytic components or co-catalytic components include, for example, calcium oxide.

[0056] The precursor composition can be extruded and calcined to produce a catalyst for the hydrogenation of wax esters to alcohols. For example, the precursor composition can be mixed with water to form a paste, and then the paste can be shaped, optionally dried, and calcined to obtain the catalyst.

[0057] Accordingly, in a fourth aspect, the present invention provides a catalyst for the hydrogenation of wax esters to alcohols, which is obtained by molding and calcining a precursor composition of the catalyst for the hydrogenation of wax esters to alcohols as described in the third aspect herein.

[0058] Detailed Implementation Plan

[0059] Implementation Scheme 1. A copper oxide powder having a particle size of at least 25.0 μm. 2 / g to 70.0 m 2 The specific surface area per g, the grain size not exceeding 150.0 Å, and the chlorine content less than 200 ppm.

[0060] Implementation Scheme 2. The copper oxide powder according to Implementation Scheme 1 has a particle size of 40.0 μm. 2 / g to 60.0 m 2 / g.

[0061] Implementation Scheme 3. The copper oxide powder according to Implementation Scheme 2 has a particle size of 45.0 μm. 2 / g to 60.0 m 2 Specific surface area per g.

[0062] Implementation Scheme 4. The copper oxide powder according to any one of Implementation Schemes 1 to 3, having a grain size of not more than 140.0 Å.

[0063] Implementation Scheme 5. The copper oxide powder according to Implementation Scheme 4 has a grain size of not more than 135.0 angstroms.

[0064] Implementation Scheme 6. The copper oxide powder according to any one of Implementation Schemes 1 to 5 has a chlorine content of not more than 180 ppm.

[0065] Implementation Scheme 7. The copper oxide powder according to Implementation Scheme 6 has a chlorine content of not more than 170 ppm.

[0066] Implementation Scheme 8. A method for preparing copper oxide powder, comprising the steps of: (1) An aqueous solution of a water-soluble copper salt and an aqueous solution of a water-soluble alkali metal carbonate are added to a precipitation reactor containing an aqueous solvent at a constant temperature in the range of 20°C to 70°C at a constant flow rate. The addition rate of the aqueous solution of the water-soluble alkali metal carbonate is controlled to maintain the pH of the system in the range of 6.0 to 9.0 and keep the pH constant. The reaction is carried out under stirring to obtain a slurry containing a precipitate. The water-soluble copper salt and the water-soluble alkali metal carbonate are used in a molar ratio in the range of 0.7 to 1.0, where the molar ratio is expressed as Cu... 2+ CO3 2- count; (2) Allow the slurry to age for 20 to 90 minutes, preferably by static aging; (3) Filter the precipitate from the slurry and wash it with deionized water; (4) The precipitate is dried and then calcined in air at a temperature in the range of 200°C to 400°C for at least 0.5 hours to obtain copper oxide powder.

[0067] Implementation Scheme 9. The method for preparing copper oxide powder according to Implementation Scheme 8, wherein the water-soluble copper salt is selected from one or more of the following: copper nitrate or its hydrate, copper sulfate or its hydrate, copper chloride or its hydrate.

[0068] Implementation Scheme 10. The method for preparing copper oxide powder according to Implementation Scheme 9, wherein the water-soluble copper salt is selected from one of the following: copper nitrate or its hydrate, copper sulfate or its hydrate, copper chloride or its hydrate.

[0069] Implementation Scheme 11. A method for preparing copper oxide powder according to any one of Implementation Schemes 8 to 10, wherein the water-soluble alkali metal carbonate is selected from one or more of the following: sodium carbonate or its hydrate, potassium carbonate or its hydrate.

[0070] Implementation Scheme 12. The method for preparing copper oxide powder according to Implementation Scheme 11, wherein the water-soluble alkali metal carbonate is sodium carbonate or its hydrate.

[0071] Implementation Scheme 13. A method for preparing copper oxide powder according to any one of Implementation Schemes 8 to 12, wherein the precipitation reaction is carried out at a constant temperature in the range of 40°C to 55°C.

[0072] Implementation Scheme 14. A method for preparing copper oxide powder according to any one of Implementation Schemes 8 to 13, wherein the addition rate of the aqueous solution of the water-soluble alkali metal carbonate is controlled to keep the pH of the system constant in the range of 7.0 to 8.0.

[0073] Implementation Scheme 15. The method for preparing copper oxide powder according to Implementation Scheme 14, wherein the addition rate of the aqueous solution of the water-soluble alkali metal carbonate is controlled to keep the pH of the system constant in the range of 7.1 to 7.5.

[0074] Implementation Scheme 16. A method for preparing copper oxide powder according to any one of Implementation Schemes 8 to 15, wherein the water-soluble copper salt and the water-soluble alkali metal carbonate are used in a molar ratio in the range of 0.8 to 0.9.

[0075] Implementation Scheme 17. A method for preparing copper oxide powder according to any one of Implementation Schemes 8 to 16, comprising aging the slurry containing precipitates obtained in step (1) for 40 to 60 minutes in step (2).

[0076] Implementation Scheme 18. A method for preparing copper oxide powder according to any one of Implementation Schemes 8 to 17, wherein in step (3), deionized water is used for washing until the conductivity of the washing solution is less than 300 µS / cm.

[0077] Implementation Scheme 19. A method for preparing copper oxide powder according to any one of Implementation Schemes 8 to 18, wherein in step (4), the calcination is carried out at a temperature in the range of 200°C to 400°C.

[0078] Implementation Scheme 20. The method for preparing copper oxide powder according to Implementation Scheme 19, wherein the calcination is carried out at a temperature in the range of 280°C to 400°C.

[0079] Implementation Scheme 21. The method for preparing copper oxide powder according to Implementation Scheme 20, wherein the calcination is carried out at a temperature in the range of 280°C to 300°C.

[0080] Implementation Scheme 22. A method for preparing copper oxide powder according to any one of Implementation Schemes 8 to 21, which is used to prepare copper oxide powder according to any one of Implementation Schemes 1 to 7.

[0081] Implementation Scheme 23. A precursor composition for a catalyst for the hydrogenation of wax esters to alcohols, comprising: (A) Copper oxide powder according to any one of embodiments 1 to 7 or copper oxide powder obtained by the method according to any one of embodiments 8 to 22, (B) Carrier; and (C) Optionally, a co-catalytic component or a co-catalytic component.

[0082] Implementation Scheme 24. The precursor composition according to Implementation Scheme 23, wherein the support is selected from silica supports and the co-catalytic component or co-catalytic component is calcium oxide.

[0083] Implementation Scheme 25. A catalyst for the hydrogenation of wax esters to alcohols, obtained by molding and calcining a precursor composition of the catalyst for the hydrogenation of wax esters to alcohols according to Implementation Scheme 23 or 24.

[0084] The present invention will be further described below with reference to specific embodiments.

[0085] Example

[0086] In the following embodiments, all operations were performed at atmospheric pressure and room temperature (ambient temperature within the experimental site) unless otherwise specified.

[0087] I. Preparation and Characterization of Copper Oxide Powder

[0088] I.1 Preparation of copper oxide powder according to the present invention

[0089] 3500 g of deionized water with a conductivity of less than 1 µS / cm was added to a reactor equipped with heating and temperature control devices. Under stirring, 5880 g of preheated water with a concentration of 3.71 mol / L (based on Cu) was introduced into the reactor at a flow rate of 5880 g / h. 2+ A copper nitrate aqueous solution (calculated as Na2CO3) was prepared, and simultaneously 9100 g of a sodium carbonate aqueous solution (Cu2CO3) preheated to the reaction temperature with a concentration of 2.36 mol / L was introduced. 2+ CO3 2- The molar ratio was approximately 0.83, and the flow rate of the sodium carbonate solution was controlled to maintain the pH in the range of 7.1-7.4. The reaction was carried out at the predetermined reaction temperature for 1 hour to form a precipitate, which was then aged in situ at 45°C for 1 hour. The slurry in the reactor was transferred to a plate and frame filter press and filtered at a pressure of at least 5 barg (gauge pressure). The filter cake was washed with deionized water until the conductivity of the washing liquid was less than 300 µS / cm. The filter cake was transferred to an oven and dried at 140°C until the moisture content was less than 0.5% (approximately 2 hours); then transferred to a rotary kiln and calcined in an air atmosphere for 40 minutes. Optionally, the copper oxide powder was particle size classified by cyclone separation to obtain copper oxide powder.

[0090] According to the general procedure, copper oxide powder according to the present invention is prepared according to the reaction temperature and calcination temperature listed in Table 2 below.

[0091] I.2 Preparation of Comparative Copper Oxide Powder

[0092] Comparative Example 1

[0093] A magnetic stir bar was placed in a 2 L beaker, and 300 g of deionized water with a conductivity of less than 1 µS / cm was added. While stirring, 500 g of a preheated (55°C) 15.5 wt% (based on Cu content) copper nitrate aqueous solution was introduced into the beaker at a flow rate of 500 g / h, and simultaneously 1000 g of a preheated (55°C) 20 wt% (based on Na₂CO₃) sodium carbonate aqueous solution was introduced, with the flow rate of the sodium carbonate aqueous solution controlled to maintain the pH in the range of 7.6-8.4. The reaction proceeded at 55°C to form a precipitate. After precipitation, the mixture was allowed to stand in situ at 70°C for 2 hours. The resulting slurry was vacuum filtered, and the filter cake was washed with deionized water until the conductivity of the washing liquid was less than 2000 µS / cm. The filter cake was transferred to an oven and dried at 140°C until the moisture content was less than 0.5%; then transferred to a static oven and calcined at 220°C for 12 hours, followed by pulverization to obtain copper oxide.

[0094] Comparative Example 2

[0095] Copper oxide powder was prepared according to the method of Comparative Example 1, except that the filter cake was washed with deionized water until the conductivity of the washing liquid was less than 5000 µS / cm.

[0096] Comparative Example 3

[0097] A magnetic stir bar was placed in a 2 L beaker, and 300 g of deionized water with a conductivity of less than 1 µS / cm was added. While stirring, 500 g of a 15.5 wt% (based on Cu content) copper nitrate aqueous solution preheated to 55°C was introduced into the beaker at a flow rate of 500 g / h, and simultaneously 1000 g of a 20 wt% (based on Na₂CO₃) sodium carbonate aqueous solution preheated to 55°C was introduced, with the flow rate of the sodium carbonate aqueous solution controlled to maintain the pH in the range of 7.6-8.4. The reaction proceeded at 55°C to form a precipitate. After precipitation, the mixture was allowed to stand in situ at 55°C for 2 hours. The resulting slurry was vacuum filtered, and the filter cake was washed with deionized water until the conductivity of the washing liquid was less than 100 µS / cm. The filter cake was transferred to an oven and dried at 140°C until the moisture content was less than 0.5%; then transferred to a static oven and calcined at 320°C for 1 hour, followed by pulverization to obtain copper oxide.

[0098] Comparative Example 4

[0099] In a 500 ml beaker, a magnetic stir bar was placed, and 300 g of water with a conductivity of less than 1 µS / cm and 3 g of ammonia (added as 10 g of concentrated ammonium hydroxide hydrate, equivalent to 0.176 mol of NH4OH) were added. Carbon dioxide gas was bubbled into the solution in the beaker and stirred until the pH of the solution reached 8.5. The solution was placed on a hot plate and heated to approximately 50°C. With thorough stirring, approximately 20 g (0.315 mol) of -325 mesh copper powder (copper to ammonia molar ratio of 1.8, copper loading of 66.6 g per liter of water) was added to the beaker, with air bubbling in simultaneously with the addition of the copper powder. The pH gradually increased during the reaction, so carbon dioxide was intermittently bubbled in to maintain a pH of approximately 8.5. After approximately 10 hours, metallic copper was no longer visible, and a green solid copper salt suspension precipitate was obtained, with the pH of the suspension remaining stably at 8.5 without further bubbling of carbon dioxide. The reaction mixture in the beaker was vacuum filtered, and the green solid filter cake was washed with deionized water until the washing filtrate was colorless. After drying the filter cake overnight in an oven at 50°C, it was transferred to a static oven and calcined at 300°C for 1 hour, and then pulverized to obtain copper oxide.

[0100] I.3 Characterization of copper oxide powder

[0101] The copper oxide powder was characterized using the instruments shown in Table 1. The specific surface area, grain size, and chlorine content of the obtained copper oxide powder are summarized in Table 2.

[0102] Table 1

[0103] II. Catalytic performance testing

[0104] II.1 Catalyst Preparation

[0105] 50 parts by weight of copper oxide, 20 parts by weight of calcium oxide, and 30 parts by weight of bentonite were mixed, and then 40% by weight of deionized water based on the mixture was added to obtain a paste. The paste was extruded into cylindrical granules, dried at 100°C for 1 hour, and then calcined at 500°C for 2 hours to obtain the catalyst.

[0106] II.2 Catalyst Activation

[0107] The catalyst was placed in a fixed-bed reactor and heated to 120°C under a nitrogen atmosphere at a rate of 5°C / min for 1 hour to remove surface-adsorbed water. Then, hydrogen was introduced into the catalyst, and the temperature was raised to 170°C at a rate of 10°C / min for 4 hours to complete the metal reduction.

[0108] II.3 Catalytic hydrogenation reaction of wax esters

[0109] The schematic equation for the hydrogenation reaction of wax esters is as follows:

[0110] High-purity hexadecyl palmitate purchased from MedChemExpress in the United States was used as the wax ester.

[0111] In a fixed-bed reactor made of 316L stainless steel, 150 mL of activated catalyst was added. The system was first purged with nitrogen three times, followed by atmosphere replacement with high-purity hydrogen (≥99.9%) until the oxygen content was below 100 ppm. The reaction was carried out at a liquid hourly space velocity of 0.6 hr. -1 The molten wax ester was fed into a fixed-bed reactor at a rate of 75 bar, and the reaction was carried out at 185°C for 30 hours.

[0112] After the reaction is complete, the pressure in the reactor is slowly released to atmospheric pressure, and then the reaction system is naturally cooled to room temperature.

[0113] The reaction products were analyzed by gas chromatography (GC) to determine the distribution of reactants and products, and the conversion rate was determined according to the following formula:

[0114] in, m1 is the amount of wax ester added; m2 represents the amount of wax ester remaining after catalytic hydrogenation.

[0115] The results are summarized in Table 2 below.

[0116] Table 2

[0117] The copper oxide powders of Comparative Example 1 and Comparative Example 2 have similar surface areas and grain sizes, but the copper oxide powder of Comparative Example 1 has significantly lower chlorine impurities. The catalyst prepared using the copper oxide powder of Comparative Example 1 showed significantly higher catalytic activity than that of the wax ester hydrogenation catalyst of Comparative Example 2. Therefore, it can be determined that lower chlorine content in copper oxide powder is beneficial to the catalytic activity of downstream catalyst products.

[0118] Compared to the copper oxide powder of Comparative Example 3, the copper oxide powder of Example 4 had a similar specific area but a significantly smaller grain size, yet a significantly higher chlorine content (nearly four times higher). Surprisingly, the catalyst prepared using the copper oxide powder of Example 4 still exhibited significantly higher catalytic activity for wax ester hydrogenation, even with a nearly four-fold higher chlorine impurity content. Similarly, compared to the copper oxide powder of Comparative Example 3, the copper oxide powder of Example 3 provided a downstream catalyst with further enhanced catalytic activity for wax ester hydrogenation, even with a higher chlorine impurity content.

[0119] The copper oxide powder of Comparative Example 4 has a higher specific surface area and a lower grain size than the copper oxide powders of Examples 3 and 4, but exhibits lower catalytic activity for wax ester hydrogenation due to its excessively high chlorine content (above 200 ppm).

Claims

1. A copper oxide powder having a particle size of at least 25.0 μm 2 / g to 70.0 m 2 The specific surface area per g, the grain size not exceeding 150.0 Å, and the chlorine content less than 200 ppm.

2. The copper oxide powder according to claim 1, having a density of 40.0 μm 2 / g to 60.0 m 2 / g, especially 45.0 m 2 / g to 60.0 m 2 Specific surface area per g.

3. The copper oxide powder according to claim 1 or 2, having a grain size of not more than 140.0 Å, particularly not more than 135.0 Å.

4. The copper oxide powder according to any one of claims 1 to 3, having a chlorine content of not more than 180 ppm, particularly not more than 170 ppm.

5. A method for preparing copper oxide powder, comprising the steps of: (1) An aqueous solution of a water-soluble copper salt and an aqueous solution of a water-soluble alkali metal carbonate are added to a precipitation reactor containing an aqueous solvent at a constant temperature in the range of 20°C to 70°C at a constant flow rate. The addition rate of the aqueous solution of the water-soluble alkali metal carbonate is controlled to maintain the pH of the system in the range of 6.0 to 9.0 and keep the pH constant. The reaction is carried out under stirring to obtain a slurry containing a precipitate. The water-soluble copper salt and the water-soluble alkali metal carbonate are used in a molar ratio in the range of 0.7 to 1.0, where the molar ratio is expressed as Cu... 2+ CO3 2- count; (2) Allow the slurry to age for 20 to 90 minutes, preferably by static aging; (3) Filter the precipitate from the slurry and wash it with deionized water; (4) The precipitate is dried and then calcined in air at a temperature in the range of 200°C to 400°C for at least 0.5 hours to obtain copper oxide powder.

6. The method for preparing copper oxide powder according to claim 5, wherein the water-soluble copper salt is selected from one or more of the following groups, preferably one: copper nitrate or its hydrate, copper sulfate or its hydrate, copper chloride or its hydrate.

7. The method for preparing copper oxide powder according to claim 5 or 6, wherein the water-soluble alkali metal carbonate is selected from one or more of the following: sodium carbonate or its hydrate, potassium carbonate or its hydrate, preferably sodium carbonate or its hydrate.

8. The method for preparing copper oxide powder according to any one of claims 5 to 7, wherein the precipitation reaction is carried out at a constant temperature in the range of 40°C to 55°C.

9. The method for preparing copper oxide powder according to any one of claims 5 to 8, wherein the addition rate of the aqueous solution of the water-soluble alkali metal carbonate is controlled to keep the pH of the system constant in the range of 7.0 to 8.0, more preferably, in the range of 7.1 to 7.

5.

10. The method for preparing copper oxide powder according to any one of claims 5 to 9, wherein the water-soluble copper salt and the water-soluble alkali metal carbonate are used in a molar ratio in the range of 0.8 to 0.

9.

11. The method for preparing copper oxide powder according to any one of claims 5 to 10, comprising in step (2) aging the slurry containing precipitate obtained in step (1) for 40 to 60 minutes.

12. The method for preparing copper oxide powder according to any one of claims 5 to 11, wherein in step (3), deionized water is used for washing until the conductivity of the washing solution is less than 300 µS / cm.

13. The method for preparing copper oxide powder according to any one of claims 5 to 12, wherein in step (4), the calcination is carried out at a temperature in the range of 200°C to 400°C, preferably 280°C to 400°C, more preferably 280°C to 300°C.

14. The method for preparing copper oxide powder according to any one of claims 5 to 13, used for preparing copper oxide powder according to any one of claims 1 to 4.

15. A precursor composition for a catalyst for the hydrogenation of wax esters to alcohols, comprising: (A) Copper oxide powder according to any one of claims 1 to 4 or copper oxide powder obtained by the method according to any one of claims 5 to 14, (B) Carrier; and (C) Optionally, a co-catalytic component or a co-catalytic component.

16. The precursor composition according to claim 15, wherein the support is selected from silica supports, and the co-catalytic component or co-catalytic component is calcium oxide.

17. A catalyst for the hydrogenation of wax esters to alcohols, obtained by molding and calcining a precursor composition of the catalyst for the hydrogenation of wax esters to alcohols according to claim 15 or 16.

Images