CN112973710A

CN112973710A - Copper-chromium catalyst, preparation method thereof and method for preparing alkanol by hydrogenating olefine aldehyde or aldehyde

Info

Publication number: CN112973710A
Application number: CN202110210058.9A
Authority: CN
Inventors: 傅送保; 姚志龙; 侯章贵; 王淇峰; 陈和; 赵雨; 薛洪健; 孙培永; 张卉; 张胜红
Original assignee: China National Offshore Oil Corp CNOOC; Beijing Institute of Petrochemical Technology; CNOOC Oil and Petrochemicals Co Ltd; CNOOC Research Institute of Refining and Petrochemicals Beijing Co Ltd; CNOOC Qingdao Heavy Oil Processing Engineering Technology Research Center Co Ltd
Current assignee: China National Offshore Oil Corp CNOOC; Beijing Institute of Petrochemical Technology; CNOOC Oil and Petrochemicals Co Ltd; CNOOC Research Institute of Refining and Petrochemicals Beijing Co Ltd; CNOOC Qingdao Heavy Oil Processing Engineering Technology Research Center Co Ltd
Priority date: 2021-02-24
Filing date: 2021-02-24
Publication date: 2021-06-18

Abstract

The invention discloses a copper-chromium catalyst, a preparation method thereof and a method for preparing alkanol by olefine aldehyde or aldehyde hydrogenation. The method comprises the following steps: providing an aqueous solution containing copper salt and chromium salt as a reaction solution, and heating for gelation to obtain a precursor; wherein anions in the copper salt and/or the chromium salt comprise nitrate radical, and the reaction liquid comprisesThe additive is a reducing substance and/or a raw material which can be decomposed to generate the reducing substance in the heating gelation process; and drying and roasting the precursor to obtain the copper-chromium catalyst. The method effectively relieves the chromium ions from NO₃ ^﹣The problem of oxidation contributes to the presence of Cu in the form of CuO in the resulting catalyst. The method is beneficial to improving the thermal stability of the catalyst in the hydrogenation activation process and avoiding the phenomenon of temperature surge. Moreover, the hydrogenation activity and selectivity of the catalyst can be further improved by the method of the invention.

Description

Copper-chromium catalyst, preparation method thereof and method for preparing alkanol by hydrogenating olefine aldehyde or aldehyde

Technical Field

The invention belongs to the technical field of catalysis, and particularly relates to a copper-chromium catalyst, a preparation method thereof and a method for preparing alkanol by olefine aldehyde or aldehyde hydrogenation.

Background

The production of aldehydes having one more carbon atom from olefins with carbon monoxide and hydrogen over a catalyst is a well known process. The aldehyde can be directly hydrogenated to obtain the alcohol, or the aldehyde can be condensed to obtain the olefine aldehyde, and the olefine aldehyde is hydrogenated to finally obtain the alcohol. One of the main uses of these alcohols is as plasticizers after esterification with terephthalic acid, in PVC, such as the traditional plasticizers 2-ethylhexanol (dioctyl phthalate, i.e. DOP), butanol (dibutyl phthalate, i.e. DBP). Since DOP and DBP have been confirmed to have potential carcinogenicity by a large number of animal experiments, the production of conventional plasticizers has been restricted in developed countries such as Europe, America, Japan, and the like in recent years, and the use of conventional plasticizers in plastic products such as medicines, foods, toy packages, and the like has been prohibited. As alternatives to 2-ethylhexanol, isononyl phthalate (DINP) and di (2-propylheptyl) phthalate (DPHP) prepared from isononyl alcohol and 2-propylheptyl alcohol have been rapidly developed, and DPHP in particular has advantages of good plasticizing performance, safety, environmental protection, low cost, and the like, compared to conventional plasticizers. Therefore, the demand of isononyl alcohol and 2-PH is increased year by year, and the method has wide market prospect. In addition, C12-C17 alcohol obtained by hydroformylation and hydrogenation of C11-C16 olefin can be used for surfactant or detergent, and the market price is higher than that of plasticizer alcohol.

The copper-chromium catalyst has higher carbonyl hydrogenation activity and selectivity of target product alcohol. Therefore, the hydrogenation technology of copper-based catalysts is mostly adopted for the hydrogenation of olefine aldehyde or aldehyde in the industry at present. Wherein butyraldehyde and octenal are subjected to gas phase hydrogenation by using a copper-zinc catalyst, and isononaldehyde and 2-propylheptenal are subjected to liquid phase hydrogenation by using a copper-chromium catalyst. Compared with a gas phase hydrogenation process, the liquid phase hydrogenation has the advantages of low energy consumption and high catalyst activity, so that the liquid phase hydrogenation catalysis of the copper-chromium is also changed into the liquid phase hydrogenation catalysis of the butyraldehyde and the octenal in recent yearsThe trend of the art. The existing process for preparing the copper-chromium catalyst by adopting a coprecipitation method has long process flow, and the loss of metal salt raw materials is large because of the difference of pH values of precipitates formed by different kinds of metal salts. In particular, chromium ions in the waste liquid are easily substituted by nitrate ions (NO)₃ ^﹣) Oxidation to form higher valent chromium ions (e.g. Cr)⁶⁺) Hidden danger exists for the environment and the personal safety of production personnel.

Disclosure of Invention

In view of the above problems in the prior art, the present invention aims to provide a copper-chromium catalyst, a preparation method thereof, and a method for preparing alkanol by hydrogenating olefine aldehyde or aldehyde. The method can improve the yield of metal ions in the raw materials, reduce the discharge of waste liquid of high-valence chromium ions, and simultaneously ensure that the copper-chromium catalyst has higher hydrogenation activity and selectivity to a target hydrogenation product.

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

in a first aspect, the present invention provides a process for the preparation of a copper chromium catalyst, said process comprising the steps of:

providing an aqueous solution containing copper salt and chromium salt as a reaction solution, and heating for gelation to obtain a precursor;

wherein anions in the copper salt and/or the chromium salt comprise nitrate radical, the reaction liquid comprises an additive, and the additive is a reducing substance and/or a raw material capable of decomposing to generate the reducing substance in the heating gelation process;

and drying and roasting the precursor to obtain the copper-chromium catalyst.

Because of the existence of reducing substances in the heating gelation process, the chromium ions are effectively relieved from NO₃ ^﹣The problem of oxidation, thus reducing, for example, CuCrO₄And the formation of copper-chromium composite oxides helps to make Cu present in the resulting catalyst in the form of CuO. The method is beneficial to improving the thermal stability of the catalyst in the hydrogenation activation process and avoiding the phenomenon of temperature surge. Furthermore, the method of the present invention can make the gel contain a small amount of reducing salt or acid molecule or residue thereof, and can be used in the subsequent bakingThe catalyst has larger specific surface area, pore volume and proper average pore diameter, thereby further improving the hydrogenation activity and selectivity of the catalyst.

As a preferable technical scheme of the method, the cation of the copper salt in the reaction liquid is Cu²⁺The cation of the chromium salt is Cr³⁺Said Cu²⁺And Cr³⁺The molar ratio of (b) is 0.6:1 to 1.5:1, for example, 0.6:1, 0.8:1, 0.9:1, 1.0:1, 1.1:1, 1.2:1, 1.3:1 or 1.5:1, and preferably 0.9:1 to 1.45: 1.

Preferably, the additive comprises any one or a combination of at least two of copper oxalate, oxalic acid, ammonium bicarbonate, ammonium oxalate or aqua ammonia, preferably any one or a combination of at least two of oxalic acid, ammonium bicarbonate, ammonium oxalate or aqua ammonia.

In the above, the additive copper oxalate has slightly different properties compared with other substances listed above, the oxalate ionized from copper oxalate can play a role in reduction, and the copper oxalate can also provide copper cations. However, the gel obtained by the method contains more oxalate, and releases more CO in the subsequent roasting process, so that the explosion in a roasting furnace is easily caused, the catalyst powder is splashed, and the potential safety hazard is even brought. Therefore, this scheme is not preferable.

Preferably, the reaction solution is prepared by the following method: mixing a copper salt solution and a chromium salt solution to obtain a metal salt solution, and then adding an additive into the metal salt solution, wherein the additive is a reducing aqueous solution;

preferably, the concentration of the solution of the copper salt and the solution of the chromium salt is independently 0.5mol/L to 2mol/L, such as 0.5mol/L, 0.7mol/L, 0.8mol/L, 1mol/L, 1.3mol/L, 1.6mol/L, 1.8mol/L, or 2mol/L, and the like.

Preferably, the reducing aqueous solution is: an aqueous solution of a salt, an acid or a base capable of decomposing the reducing substance to produce a gaseous phase.

Preferably, the reducing aqueous solution comprises any one of or a mixture of at least two of aqueous ammonium bicarbonate, aqueous ammonium oxalate, oxalic acid or aqueous ammonia. However, the present invention is not limited to the above-mentioned materials, and other salts, acids or alkaline liquids which are generally used in the art and can be decomposed to produce strongly reducing substances such as ammonia and carbon monoxide may be used in the present invention.

Preferably, the concentration of the reducing aqueous solution is 0.5mol/L to 2mol/L, for example, 0.5mol/L, 0.7mol/L, 0.8mol/L, 1mol/L, 1.2mol/L, 1.5mol/L, 1.8mol/L, or 2 mol/L.

Preferably, the addition amount of the reducing aqueous solution satisfies: the amount of the total amount of ammonium ions and/or oxalate ions added and NO contained in the reaction solution₃ ^﹣The molar ratio of (a) to (b) is 1:1 to 1.1:1, for example 1.01:1, 1.02:1, 1.03:1, 1.05:1, 1.07:1 or 1.1: 1.

By controlling the reaction temperature of heating gelation and the addition amount of the reducing aqueous solution, the morphology, the particle size and the dispersion of CuO crystal grains of the catalyst can be regulated, so that the catalyst has larger specific surface area, smaller crystal grain size and good dispersion uniformity of the CuO crystal grains and can contact more active centers, and therefore, the catalyst can obtain higher hydrogenation activity and selectivity of a target hydrogenation product.

Due to the fact that the gel contains the reducing salt or acid molecules or residues thereof by adding the reducing aqueous solution in a proper amount, the gel can play a pore-forming role in subsequent roasting, the pore volume and the pore diameter can be regulated and controlled by regulating the type and the content of the reducing aqueous solution, the catalyst with larger pore volume and proper average pore diameter can be obtained, and the hydrogenation activity and the selectivity of the catalyst can be further improved.

Preferably, the thermal gelation process is accompanied by the continuous addition of additives;

as a preferred technical scheme of the method, the preparation method of the precursor comprises the following steps:

and mixing the solution of the copper salt and the solution of the chromium salt to obtain a metal salt solution, heating to a certain temperature, and continuously adding the additive until gel is obtained.

Preferably, the heating to a certain temperature is heating to 80 ℃ to 95 ℃, such as 80 ℃, 82 ℃, 85 ℃, 88 ℃, 90 ℃, 93 ℃ or 95 ℃ and the like.

Preferably, the continuous addition is accompanied by stirring.

Preferably, the gas phase species generated during said thermal gelation process are transferred out of the reaction chamber.

Preferably, the volume of the liquid water obtained by condensing the removed gas phase substances is 70% to 95%, for example 70%, 72%, 75%, 80%, 85%, 90% or 95%, etc., preferably 75% to 90%, based on the total volume of the reaction liquid. The total volume of the reaction solution as referred to herein means the total volume of the respective substances participating in the reaction, for example, the volume of the aqueous solution of the copper salt and the chromium salt, and the volume of the reducing aqueous solution to be added. Whether the reducing aqueous solution is added at one time, stepwise, or continuously dropwise, the reducing solution is calculated as the total volume of addition when the total volume is calculated here. For example, when the aqueous ammonia is continuously added dropwise and a total volume of 1000mL is added, the volume of the aqueous ammonia is 1000mL when the total volume is calculated here.

When the volume percentage of the collected condensed water amount to the total amount of the reaction solution and the reducing aqueous solution is in an appropriate range, the heating is stopped to obtain a gel. This allows the water content of the gel to be tailored and the resulting catalyst, after subsequent drying and calcination, can have improved pore volume and pore size distribution.

The transferred gas phase contains water, and the water evaporated by heating can be recycled after being cooled, so that resources are saved. Preferably, the temperature for drying the precursor is 80 ℃ to 140 ℃, for example 80 ℃, 90 ℃, 100 ℃, 110 ℃, 120 ℃, 130 ℃ or 140 ℃, etc.

Preferably, the temperature for the calcination of the precursor is 300 ℃ to 400 ℃, such as 300 ℃, 320 ℃, 330 ℃, 340 ℃, 350 ℃, 360 ℃, 375 ℃, 380 ℃, 390 ℃, or 400 ℃, and the like.

In some embodiments, the fired product may also be subjected to a shaping process.

As a further preferred technical solution of the method of the present invention, the method comprises the steps of:

providing an aqueous solution containing copper nitrate and chromium nitrate as a pre-reaction solution;

heating the reaction liquid to 80-95 ℃, continuously adding a reducing aqueous solution into the pre-reaction liquid under the condition of stirring until gel is obtained, and drying and roasting the gel to obtain the copper-chromium catalyst;

gas-phase substances generated by the heating reaction are transferred out of the reaction chamber in real time;

wherein the reducing aqueous solution is selected from any one of ammonium bicarbonate aqueous solution, ammonium oxalate aqueous solution, oxalic acid or ammonia water or a mixture of at least two of the ammonium bicarbonate aqueous solution, the ammonium oxalate aqueous solution and the oxalic acid or the ammonia water; the addition amount of the reducing aqueous solution satisfies the amount of ammonium ions, oxalate or the total substance thereof added and the nitrate NO contained in the reaction solution₃ ^﹣The molar ratio of (A) to (B) is 0.9:1 to 1.5: 1.

The preparation method of the copper-chromium catalyst provided by the invention takes copper nitrate and chromium nitrate as raw materials, forms gel through heating and hydrolysis, and then obtains the copper-chromium catalyst through drying, roasting and optional forming treatment, so that the production process is simple, particularly the yield of metal ions in the raw materials is high, the loss is small, meanwhile, the generation of waste liquid containing metal ions is remarkably reduced or even basically eliminated, and the problem of waste liquid treatment is effectively relieved. The water evaporated by heating can be recycled after being cooled, so that the resources are saved.

In a second aspect, the present invention provides a copper-chromium catalyst prepared by the method of the first aspect, wherein the copper-chromium catalyst comprises CuO and Cr₂O₃；

Preferably, the copper element in the copper-chromium catalyst exists in the form of CuO, and the BET specific surface area of the copper-chromium catalyst is more than or equal to 50m²In g, e.g. 50m²/g、60m²/g、65m²/g、70m²/g、80m²In g or 100m²And/g, etc.

Preferably, the CuO and Cr₂O₃The mass ratio of (a) to (b) is 40:60 to 60:40, for example 40:60, 45:55, 48:52, 50:50, 55:45 or 60: 40.

In some embodiments, the copper chromium catalyst isPore volume is more than or equal to 0.3cm³In g, e.g. 0.3cm³/g、cm³/g、0.4cm³/g、0.5cm³/g、0.6cm³/g、0.8cm³In g or 1.0cm³And/g, etc.

In some embodiments, the copper chromium catalyst has an average pore size of 14nm to 17nm, such as 14nm, 15nm, 16nm, or 17nm, and the like.

In a third aspect, the present invention provides a process for the hydrogenation of an enal or aldehyde to produce an alkanol using the copper chromium catalyst of the second aspect.

Preferably, the alkenals include any one or a combination of two of 2-propyl-2-heptenal and 2-ethylhexenal, but are not limited to the alkenals listed above, and other alkenals from C3 to C20 are also suitable for use in the present invention.

Preferably, the aldehydes include any one or a combination of at least two of isobutyraldehyde, n-butyraldehyde or isononaldehyde, but are not limited to the above-listed aldehydes, and other aldehydes of C3 to C20 are also suitable for the present invention.

It will be understood by those skilled in the art that hydrogenation of the enal or aldehyde results in the corresponding alkanol, such as 2-propylheptanol, 2-ethylhexanol, n-butanol, isobutanol, isononanol or other C3-C20 alkanols.

Preferably, in the method, the conditions of hydrogenation catalysis are as follows: the molar ratio of hydrogen to the enal or aldehyde is 2 to 20, such as 2, 4, 5, 6, 8, 10, 11, 12, 13, 15, 18, or 20; the reaction temperature is 140 ℃ to 200 ℃, for example, 140 ℃, 150 ℃, 160 ℃, 180 ℃, 190 ℃ or 200 ℃, etc.; the reaction pressure is 2MPa to 5MPa, such as 2MPa, 3MPa, 3.5MPa, 4MPa or 5 MPa; the space velocity of the feeding volume is 0.1h^-1～1h^-1，0.1h^-1、0.2h^-1、0.3h^-1、0.5h^-1、0.6h^-1、0.8h^-1Or 1h^-1And the like.

The method for preparing corresponding alkanol by hydrogenating the olefine aldehyde or the aldehyde can obtain higher olefine aldehyde or aldehyde conversion rate and corresponding alkanol selectivity due to the copper-chromium catalyst in the second aspect.

Compared with the prior art, the invention has the following beneficial effects:

the preparation method of the copper-chromium catalyst provided by the invention takes the copper salt and/or chromium salt containing nitrate as raw materials, forms gel by heating and hydrolyzing, and then obtains the catalyst by drying, roasting and optionally forming treatment, so that the production process is simple, particularly the yield of metal ions in the raw materials is high, the loss is small, meanwhile, the generation of waste liquid containing metal ions is remarkably reduced or even basically eliminated, and the problem of waste liquid treatment is effectively relieved. Meanwhile, the copper-chromium catalyst has higher hydrogenation activity and selectivity to a target hydrogenation product.

Drawings

FIG. 1 is a flow chart of a method of making a copper chromium catalyst in one embodiment of the invention.

Fig. 2 is an X-ray diffraction (XRD) pattern of the copper chromium catalyst.

Detailed Description

The technical scheme of the invention is further explained by the specific implementation mode in combination with the attached drawings.

In order to make the objects, technical solutions and advantageous effects of the present invention more clear, the present invention is described in detail with reference to specific embodiments below. It should be understood that the embodiments described in this specification are only for the purpose of explaining the present invention and are not intended to limit the present invention.

For the sake of brevity, only some numerical ranges are explicitly disclosed herein. However, any lower limit may be combined with any upper limit to form ranges not explicitly recited; and any lower limit may be combined with any other lower limit to form a range not explicitly recited, and similarly any upper limit may be combined with any other upper limit to form a range not explicitly recited. Also, although not explicitly recited, each point or individual value between endpoints of a range is encompassed within the range. Thus, each point or individual value can form a range not explicitly recited as its own lower or upper limit in combination with any other point or individual value or in combination with other lower or upper limits.

In the description herein, it is to be noted that, unless otherwise specified, "above" and "below" are inclusive and "one or more" of "the" means "two or more.

The inventor provides an efficient and clean copper-chromium catalyst and a preparation method thereof by deeply researching the nature of an active center of the copper-chromium catalyst, the reaction type in the preparation process of the catalyst and the like. Referring to fig. 1, a method for preparing a copper-chromium catalyst according to an embodiment of the present invention includes:

s10: providing an aqueous solution comprising a copper salt and a chromium salt;

s20: providing a reducing aqueous solution;

s30: forming a gel;

s40: drying;

s50: and (4) roasting.

In the step S10 of providing the reaction solution, the method includes: an aqueous solution containing a copper salt and a chromium salt, wherein at least one of the copper salt and the chromium salt should have a nitrate as an anion, for example, an aqueous solution of copper nitrate and chromium nitrate may be used as a reaction solution. The reaction solution can be prepared by a method known in the art. As an example, copper nitrate is dissolved in water to obtain an aqueous copper nitrate solution; dissolving chromium nitrate in water to obtain chromium nitrate aqueous solution; and mixing the copper nitrate aqueous solution and the chromium nitrate aqueous solution to obtain a reaction solution.

In some embodiments, the concentration of the aqueous copper nitrate solution is 0.5mol/L to 2 mol/L. Optionally, the concentration of the aqueous copper nitrate solution is 0.5mol/L to 1.2mol/L, 0.8mol/L to 1.5mol/L, or 1mol/L to 2 mol/L.

In some embodiments, the concentration of the aqueous solution of chromium nitrate is from 0.5mol/L to 2 mol/L. Optionally, the concentration of the chromium nitrate aqueous solution is 0.5mol/L to 1.2mol/L, 0.8mol/L to 1.5mol/L, or 1mol/L to 2 mol/L.

The concentration of copper nitrate and chromium nitrate in the reaction liquid is in a proper range, which is beneficial to leading copper oxide CuO and chromium oxide Cr in the obtained copper-chromium catalyst to be in₂O₃Is uniformly dispersed. In addition, the concentration of copper nitrate and chromium nitrate in the reaction liquid is higher, which is beneficial to improving the yield of the copper-chromium catalyst.

In some embodiments, Cu in the reaction liquid²⁺And Cr³⁺In a molar ratio of 0.6:11.5: 1. Alternatively, Cu in the reaction solution²⁺And Cr³⁺Is 0.9:1 to 1.45:1, or 1.1:1 to 1.5: 1. Cu in reaction solution²⁺And Cr³⁺The molar ratio of (A) to (B) is in a proper range, which is favorable for the CuO and Cr in the obtained copper-chromium catalyst₂O₃The proportion of the catalyst is proper, so that the catalyst obtains higher hydrogenation activity and selectivity.

In another embodiment, the reaction solution may be obtained by dissolving copper nitrate and chromium nitrate in water.

In the step S20 of providing the reducing aqueous solution, a salt or acid aqueous solution may be formulated using a method known in the art. As a specific example, the corresponding salt or acid or a mixture thereof is dissolved in water to give the corresponding aqueous solution.

In some embodiments, the concentration of the salt, acid, base, or mixture thereof in the reducing aqueous solution may be between 0.5mol/L and 2 mol/L. Alternatively, the concentration of the salt, acid, base, or mixture thereof in the reducing aqueous solution may be 0.5 to 1.2mol/L, 0.8 to 1.5mol/L, or 1 to 2 mol/L.

In each aqueous solution, the water may be selected from distilled water, deionized water, and the like.

In the step S30 of forming a gel, the reaction liquid is heated to 80 to 95 ℃, illustratively, while continuously adding the reducing aqueous solution to the reaction liquid under stirring, until a gel is obtained.

In some embodiments, the continuous addition may be dropwise or at a predetermined flow rate, so that a predetermined amount of the reducing aqueous solution is added to the reaction solution throughout the reaction period (reaction start to reaction end) in which the gel is formed.

In some embodiments, the amount of the reducing aqueous solution added is such that the amount of ammonium ions, oxalate or the total thereof added and nitrate NO contained in the reaction solution₃ ^﹣The molar ratio of (A) to (B) is 0.9:1 to 1.5: 1. Optionally, added in an amount satisfying the amount of ammonium ions, oxalate or the total thereof added and NO contained in the reaction liquid₃ ^﹣The molar ratio of (a) to (b) is 0.95:1 to 1.3:1, 1:1 to 1.2:1, or 1:1 to 1.1: 1. Optionally, the reaction temperature is 80-90 DEG C85-95 ℃ or 90-95 ℃.

In step S30, the reaction chamber for forming the gel may be a stirred tank reactor.

The heating may be by a constant temperature oil bath. Alternatively, the reaction vessel may be provided with a heating jacket, and a heating medium is introduced into the heating jacket for heating. The heating medium can be selected from heat transfer oil, hot water, etc.

In step S30, the copper nitrate and the chromium nitrate undergo hydrolysis reaction by heating to form a gel. Meanwhile, the reducing aqueous solution is used as a reducing agent, and an appropriate amount of reducing aqueous solution is continuously added into the reaction solution in the hydrolysis reaction process to play a role in reducing, so that the trivalent chromium ions Cr can be relieved³⁺Quilt NO₃ ^﹣The problem of oxidation, thus reducing, for example, CuCrO₄And the formation of the copper-chromium composite oxide is beneficial to enabling Cu in the obtained catalyst to exist in a CuO form, so that the catalyst with higher hydrogenation catalytic activity and selectivity is obtained. In addition, the catalyst may be, for example, CuCrO₄And the reduction of the copper-chromium composite oxides can also improve the thermal stability of the catalyst in the hydrogenation activation process, and avoid the phenomenon of temperature surge, thereby being beneficial to obtaining the catalyst with uniform physicochemical properties and stable hydrogenation catalytic performance.

By reasonably controlling the reaction temperature and the addition amount of reducing salt or acid or the mixture thereof, CuO and Cr in the obtained catalyst can be ensured₂O₃Are more uniformly dispersed. The catalyst has larger specific surface area and smaller CuO crystal grains, and can contact with active centers to be increased, thereby obtaining higher hydrogenation activity and selectivity of target hydrogenation products.

The addition of a proper amount of reducibility can also enable the gel to contain a small amount of reducing salt or acid molecules or residues thereof, and the gel can play a pore-forming role in subsequent roasting, so that the catalyst can also have a larger pore volume and a proper average pore diameter, and the hydrogenation activity and selectivity of the catalyst can be further improved.

During the research process, the inventor also finds that copper oxalate and chromium nitrate can be used to form gel through heating hydrolysis reaction. The oxalate ionized from the copper oxalate can play the role of the reduction. However, the gel obtained by the method contains more oxalate, and releases more CO in the subsequent roasting process, so that the explosion in a roasting furnace is easily caused, the catalyst powder is splashed, and the potential safety hazard is even brought. Therefore, this scheme is not preferable.

In some embodiments, at S30, further comprising: and removing the gas-phase substances generated by heating out of the reaction chamber in real time. The removal of the gas phase from the reaction chamber during the reaction may facilitate the hydrolysis reaction to form a gel. The gas phase substance comprises water and NO_xAnd the like. The vapor phase material is condensed to recover the evaporated water for reuse. As an example, the collected condensed water may be reused as water for preparing the aqueous solution. And the cooled noncondensable gas is purified and discharged.

In some embodiments, the percentage of the volume of liquid water resulting from condensation of the gas phase removed in step S30 to the total volume of the aqueous solution comprising the copper and chromium salts and the aqueous reducing solution is from 70% to 95%. Optionally, the percentage of the volume of liquid water condensed from the gas phase substance removed in step S30 to the total volume of the aqueous solution containing copper salt and chromium salt and the reducing aqueous solution is 75% to 90%, 78% to 92%, or 80% to 90%. When the volume percentage of the collected condensed water amount to the total amount of the reaction solution and the reducing aqueous solution is in an appropriate range, the heating is stopped to obtain a gel. This allows the water content of the gel to be tailored and the resulting catalyst, after subsequent drying and calcination, can have improved pore volume and pore size distribution. In addition, the reaction endpoint can be conveniently monitored by production personnel according to the amount of the condensed water.

In step S40, the gel may be dried at a temperature of 80 ℃ to 140 ℃. Optionally, the drying temperature is from 100 ℃ to 140 ℃. Alternatively, the drying time is from 6 hours to 15 hours, or from 10 hours to 12 hours. As a specific example, the gel was dried at 120 ℃ for 12 hours.

The gel may be dried using equipment known in the art, such as a thermostated drying oven.

In step S50, the dried gel may be calcined at a temperature of 300 to 400 ℃. Optionally, the temperature of the calcination is 300 ℃ to 350 ℃. Alternatively, the time of calcination is from 3 hours to 6 hours, or from 4 hours to 5 hours. As a specific example, the dried gel is calcined at 300 to 350 ℃ for 4 hours.

The dried gel may be calcined using equipment known in the art, such as a muffle furnace.

The powder obtained after roasting can be directly used as a catalyst. In some embodiments, the step of shaping the powder is optionally included after the firing. The copper-chromium catalyst with the required morphology can be obtained by the skilled person through tabletting or other forming methods according to the requirement. As an example, the powder is molded by a tablet method. The pressure of the tablet can be 3MPa to 8MPa, or 5MPa to 7MPa, and the like.

In the preparation method of the copper-chromium catalyst provided by the embodiment of the invention, copper nitrate and chromium nitrate are used as raw materials, gel is formed by heating and hydrolyzing, and then the catalyst is obtained by drying, roasting and optionally forming, so that the production process is simple, particularly, the yield of metal ions in the raw materials is high, the loss is small, meanwhile, the generation of waste liquid containing metal ions is remarkably reduced or even basically eliminated, and the problem of waste liquid treatment is effectively relieved.

In another embodiment of the present invention, there is provided a copper-chromium catalyst comprising CuO and Cr₂O₃。

In some embodiments, the copper element of the copper-chromium catalyst is present as CuO, and the BET specific surface area of the catalyst is greater than or equal to 50m²(ii) in terms of/g. Alternatively, the catalyst has a BET specific surface area of 50m²/g～55m²/g，52m²/g～55m²Per g, or 50m²/g～54m²/g。

Cu exists in a CuO form, so that the thermal stability of the catalyst in the hydrogenation activation process is improved, the phenomenon of temperature surge is avoided, and the hydrogenation activation catalyst with uniform physicochemical properties and stable hydrogenation catalytic performance is obtained. Moreover, the specific surface area of the catalyst is large, indicating that CuO and Cr are contained in the catalyst₂O₃Uniformly dispersed crystal grain rulerIt is smaller and can contact more active sites. Therefore, the catalyst can obtain higher hydrogenation activity and selectivity of a target hydrogenation product.

In some embodiments, the pore volume of the catalyst is 0.3cm or more³(ii) in terms of/g. Alternatively, the pore volume of the catalyst is 0.3cm³/g～0.4cm³In g, or 0.3cm³/g～0.35cm³(ii) in terms of/g. The catalyst has larger pore volume, further showing that CuO and Cr in the catalyst²O³The dispersion uniformity of (a) is higher, thereby contributing to improvement of the hydrogenation activity and selectivity of the catalyst.

In some embodiments, the catalyst has an average pore size of 14nm to 17 nm. Optionally, the catalyst has an average pore size of 15nm to 16.5 nm. The average pore diameter of the catalyst is in a proper range, so that the hydrogenation activity and selectivity of the catalyst can be further improved.

In some embodiments, the catalyst comprises CuO and Cr₂O₃The mass ratio of (A) to (B) is 40: 60-60: 40. Alternatively, CuO and Cr are present in the catalyst₂O₃The mass ratio of (A) to (B) is 50: 50-60: 40, or 55: 45-60: 40. CuO and Cr in Cu-Cr catalyst₂O₃The proportion of the catalyst is proper, so that the catalyst can obtain higher hydrogenation activity and selectivity.

In this context, the phase of the catalyst can be determined by X-ray diffraction (XRD). A powder X-ray diffractometer model Bruker AXSD8 was used. The test conditions were as follows: the Cu-Kalpha target has the wavelength lambda of 0.15418nm, the working current of 40mA, the voltage of 40kV, the scanning speed of 4 DEG/min, the scanning step of 0.02 DEG and the scanning range of 20 DEG-80 deg. The particle size of the catalyst sample is more than 180 meshes.

In this context, the specific surface area, pore volume (also known as pore volume), and average pore diameter of the catalyst are all well known in the art and can be measured using methods and equipment known in the art. For example, Autosorb-iQ type physical and chemical adsorbers from Conta instruments (Quantachrome, USA). An exemplary test method is as follows: before the test, the catalyst sample is vacuumized to <1Pa, degassed at 300 ℃ for 3h under vacuum condition, and then subjected to nitrogen physical adsorption at liquid nitrogen-196 ℃ to obtain the adsorption/desorption curve of the catalyst powder. The specific surface area is calculated by the BET (Brunner-Emmet-Teller) method, and the pore size distribution is calculated by the BJH (Barret-Joyner-Halenda) method.

In yet another embodiment, the invention provides a process for the hydrogenation of an enal or aldehyde to a corresponding alkanol. The hydrogenation catalyst used for preparing the corresponding alkanol by hydrogenating the olefine aldehyde comprises the copper-chromium catalyst.

Examples of the enal include enals having 3 to 20 carbon atoms. Optionally, the enal has 5 to 15 carbon atoms, 8 to 12 carbon atoms, or the like. For example, the enal is decenal. In some embodiments, the enal is 2-propyl-2-heptenal. Correspondingly, the alkanol is 2-propylheptanol.

The method for preparing corresponding alkanol by olefine aldehyde hydrogenation adopts the copper-chromium catalyst, so that higher olefine aldehyde conversion rate and alkanol selectivity can be obtained.

The hydrogenation catalytic conditions can be determined by those skilled in the art according to the principles of the olefine aldehyde hydrogenation reaction. In some embodiments, the enal is 2-propyl-2-heptenal, the alkanol is 2-propyl heptanol, and the hydrocatalytic conditions may be: the molar ratio of the hydrogen to the 2-propyl-2-heptenal is 5-20; the reaction temperature is 140-200 ℃; the reaction pressure is 2 MPa-5 MPa; the feeding volume airspeed is 0.1h < -1 > to 1h < -1 >.

The enal hydrogenation catalysis can be carried out in equipment known in the art. Such as fixed bed reactors and the like.

Examples

The present disclosure is more particularly described in the following examples that are intended as illustrations only, since various modifications and changes within the scope of the present disclosure will be apparent to those skilled in the art. Unless otherwise indicated, all parts, percentages, and ratios reported in the following examples are on a weight basis, and all reagents used in the examples are commercially available or synthesized according to conventional methods and can be used directly without further treatment, and the equipment used in the examples is commercially available.

Preparation of catalyst

Example 1

263.98mL of copper nitrate solution (with the concentration of 1.0mol/L) and 184.22mL of chromium nitrate solution (with the concentration of 1.0mol/L) are respectively measured and placed in a glass reaction kettle with a 600mL volume and a stirring and heating jacket, wherein the mass ratio of copper to chromium is 1.43: 1; starting stirring and introducing heat conducting oil, and controlling the temperature in the reaction kettle to be 90 ℃; simultaneously, adding 1186mL of oxalic acid solution (the concentration is 1.0mol/L, and the molar ratio of oxalic acid to total nitrate radical is 1.1:1) dropwise into the reaction kettle; the evaporated water was collected by condensation to 1300mL and the stirring was stopped to give 175g of gel. Placing the obtained gel in an enamel tray, and drying at 120 ℃ for 12 hours; the dried solid was calcined at 300 ℃ for 4 hours to give a total of 34.8g of black powder A and a metal ion yield of 99.42% (metal ion yield calculated according to the following formula: 100% by mass of black powder A/(molecular weight of copper oxide 0.26398+ molecular weight of chromium oxide 0.18422/2)). And tabletting the black powder A by adopting a tabletting forming mode, wherein the tabletting pressure is 7.0MPa, and thus the catalyst A is obtained.

In the catalyst A, copper oxide CuO and chromium oxide Cr₂O₃The mass ratio of (A) to (B) is 60: 40.

Example 2

Respectively measuring 241.98mL of copper nitrate solution (with the concentration of 1.0mol/L) and 207.25mL of chromium nitrate solution (with the concentration of 1.0mol/L), and placing the solutions in a glass reaction kettle with a clamp sleeve and the volume of which is 600mL, wherein the mass ratio of copper to chromium is 1.17: 1; starting stirring and introducing heat conducting oil, and controlling the temperature in the reaction kettle to be 80 ℃; simultaneously, dripping 1106mL of oxalic acid solution (the concentration is 1.0mol/L, and the molar ratio of oxalic acid to total nitrate radical is 1.0:1) into the reaction kettle; the evaporated water was collected by condensation to 1230mL and stirring was stopped to yield 174g of a gel. The resulting gel was placed in an enamel plate and dried at 120 ℃ for 12 hours, and the dried solid was calcined at 350 ℃ for 4 hours to obtain a total of 34.9g of black powder B (metal ion yield 99.6%). And tabletting the black powder B by adopting a tabletting forming mode, wherein the tabletting pressure is 7.0MPa, and thus obtaining the catalyst B.

Example 3

This example 3 differs from example 1 only in that the total amount of oxalic acid solution was 565mL, and black powder C was obtained after calcination, with a metal ion yield of 99.28%.

And tabletting the black powder C by adopting a tabletting forming mode, wherein the tabletting pressure is 7.0MPa, and thus obtaining the catalyst C.

Example 4

Respectively measuring 241.98mL of copper nitrate solution (with the concentration of 1.0mol/L) and 207.25mL of chromium nitrate solution (with the concentration of 1.0mol/L), and placing the solutions in a glass reaction kettle with a clamp sleeve and the volume of which is 600mL, wherein the mass ratio of copper to chromium is 1.17: 1; starting stirring and introducing heat conducting oil, and controlling the temperature in the reaction kettle to be 80 ℃; simultaneously, 1659mL of oxalic acid solution (the concentration is 1.0mol/L, and the molar ratio of oxalic acid to total nitrate radical is 1.5:1) is dripped into the reaction kettle; the evaporated water was collected by condensation to 1780mL and the stirring was stopped to yield 175g of gel. The resulting gel was placed in an enamel plate and dried at 120 ℃ for 12 hours, and the dried solid was calcined at 350 ℃ for 4 hours to obtain a total of 34.9g of black powder E (metal ion yield 99.6%). And tabletting the black powder F by adopting a tabletting forming mode, wherein the tabletting pressure is 7.0MPa, and thus the catalyst F is obtained.

Example 5

Respectively measuring 241.98mL of copper nitrate solution (with the concentration of 1.0mol/L) and 207.25mL of chromium nitrate solution (with the concentration of 1.0mol/L), and placing the solutions in a glass reaction kettle with a clamp sleeve and the volume of which is 600mL, wherein the mass ratio of copper to chromium is 1.17: 1; starting stirring and introducing heat conducting oil, and controlling the temperature in the reaction kettle to be 80 ℃; simultaneously, 996mL of total oxalic acid solution (the concentration is 1.0mol/L, and the molar ratio of oxalic acid to total nitrate radical is 0.9:1) is dripped into the reaction kettle; the evaporated water was collected by condensation to 1130mL and stirring was stopped to yield 173g of gel. The obtained gel was placed in an enamel tray and dried at 120 ℃ for 12 hours, and the dried solid was calcined at 350 ℃ for 4 hours to obtain a total of 34.9G of black powder G (metal ion yield 99.6%). And tabletting the black powder G by adopting a tabletting forming mode, wherein the tabletting pressure is 7.0MPa, and thus obtaining the catalyst G.

Example 6

263.98mL of copper nitrate solution (with the concentration of 1.0mol/L) and 184.22mL of chromium nitrate solution (with the concentration of 1.0mol/L) are respectively measured and placed in a glass reaction kettle with a 600mL volume and a stirring and heating jacket, wherein the mass ratio of copper to chromium is 1.43: 1; starting stirring and introducing heat conducting oil, and controlling the temperature in the reaction kettle to be 90 ℃; simultaneously, 593mL of ammonium oxalate solution (the concentration is 1.0mol/L, and the molar ratio of the sum of the oxalic acid and ammonium ion mass to the total nitrate radical is 1.1:1) is dripped into the reaction kettle; the evaporated water was collected by condensation to 730mL and the stirring was stopped to give 174g of a gel. Placing the obtained gel in an enamel tray, and drying at 120 ℃ for 12 hours; the dried solid was calcined at 300 ℃ for 4 hours to obtain a total of 34.9g of black powder J (metal ion yield 99.82%). And tabletting the black powder J by adopting a tabletting forming mode, wherein the tabletting pressure is 7.0MPa, and thus the catalyst J is obtained.

Copper oxide CuO and chromium oxide Cr in catalyst J₂O₃The mass ratio of (A) to (B) is 60: 40.

Example 7

263.98mL of copper nitrate solution (with the concentration of 1.0mol/L) and 184.22mL of chromium nitrate solution (with the concentration of 1.0mol/L) are respectively measured and placed in a glass reaction kettle with a 600mL volume and a stirring and heating jacket, wherein the mass ratio of copper to chromium is 1.43: 1; starting stirring and introducing heat conducting oil, and controlling the temperature in the reaction kettle to be 90 ℃; simultaneously, dropwise adding 1186mL of ammonium bicarbonate solution (the concentration is 1.0mol/L, and the molar ratio of ammonium ions to total nitrate radicals is 1.1:1) into the reaction kettle; the evaporated water was collected by condensation to 1300mL and the stirring was stopped to give 174g of a gel. Placing the obtained gel in an enamel tray, and drying at 120 ℃ for 12 hours; the dried solid was calcined at 300 ℃ for 4 hours to obtain a total of 34.8g of black powder K (metal ion yield 99.42%). And tabletting the black powder K by adopting a tabletting forming mode, wherein the tabletting pressure is 7.0MPa, so that the catalyst K is obtained.

Copper oxide CuO and chromium oxide Cr in catalyst K₂O₃The mass ratio of (A) to (B) is 60: 40.

Example 8

263.98mL of copper nitrate solution (with the concentration of 1.0mol/L) and 184.22mL of chromium nitrate solution (with the concentration of 1.0mol/L) are respectively measured and placed in a glass reaction kettle with a 600mL volume and a stirring and heating jacket, wherein the mass ratio of copper to chromium is 1.43: 1; starting stirring and introducing heat conducting oil, and controlling the temperature in the reaction kettle to be 90 ℃; simultaneously, dropwise adding an ammonia water solution (the concentration is 1.0mol/L, and the molar ratio of ammonium ions to total nitrate radicals is 1.1:1) with the total amount of 1186mL into the reaction kettle; the evaporated water was collected by condensation to 1300mL and the stirring was stopped to give 174g of a gel. Placing the obtained gel in an enamel tray, and drying at 120 ℃ for 12 hours; the dried solid was calcined at 300 ℃ for 4 hours to obtain a total of 34.8g of black powder L (metal ion yield 99.42%). And tabletting the black powder L by adopting a tabletting forming mode, wherein the tabletting pressure is 7.0MPa, and thus the catalyst L is obtained.

Copper oxide CuO and chromium oxide Cr in catalyst L₂O₃The mass ratio of (A) to (B) is 60: 40.

Comparative example 1

263.98mL of copper nitrate solution (with the concentration of 1.0mol/L) and 184.22mL of chromium nitrate solution (with the concentration of 1.0mol/L) are respectively measured and placed in a glass reaction kettle with a stirring and heating jacket and a volume of 600mL, wherein the molar ratio of copper to chromium is 1.43: 1; starting stirring and introducing heat conducting oil, and controlling the temperature in the reaction kettle to be 90 ℃; the evaporated water was collected by condensation to 270mL and stirring was stopped to give 174g of a gel. The resulting gel was placed in an enamel plate and dried at 120 ℃ for 12 hours, and the dried solid was calcined at 300 ℃ for 4 hours to obtain 34.7g in total of a brown powder D (metal ion yield 99.13%). And tabletting the black powder D by adopting a tabletting forming mode, wherein the tabletting pressure is 7.0MPa, and thus obtaining the catalyst D.

The comparative example differs from example 1 in that no oxalic acid solution was added and the amount of water evaporated by condensing and collecting was adjusted to ensure that the quality of the resulting gel was the same as example 1.

Comparative example 2

263.98mL of copper nitrate solution (with the concentration of 1.0mol/L) and 184.22mL of chromium nitrate solution (with the concentration of 1.0mol/L) are respectively measured and injected into a stirred glass reaction kettle with the volume of 2000mL through a metering pump at the speed of 4.5mL/min and 3.1mL/min, wherein the mass ratio of copper to chromium is 1.43: 1; simultaneously, injecting 1.0mol/L sodium bicarbonate solution as a precipitating agent into the reaction kettle at the speed of 18mL/min, wherein the injection amount of the precipitating agent is 1080mL, and the pH value of the reaction system is maintained to be 6.0-6.5; after the precipitation reaction was completed, it was aged at room temperature for 12 hours, then filtered and washed with deionized water to neutrality. The resulting precipitate was placed in an enamel tray and dried at 120 ℃ for 12 hours, and the dried solid was calcined at 300 ℃ for 4 hours to obtain a total of 31.5g of black powder E (metal ion yield 89%). And tabletting the black powder E by adopting a tabletting forming mode, wherein the tabletting pressure is 7.0MPa, and thus obtaining the catalyst E.

Comparative example 3

Respectively measuring 241.98mL of copper nitrate solution (with the concentration of 1.0mol/L) and 207.25mL of chromium nitrate solution (with the concentration of 1.0mol/L), and placing the solutions in a glass reaction kettle with a clamp sleeve and the volume of which is 2000mL, wherein the mass ratio of copper to chromium is 1.17: 1; starting stirring and introducing heat conducting oil, and controlling the temperature in the reaction kettle to be 80 ℃; simultaneously, adding 1106mL of oxalic acid solution (the concentration is 1.0mol/L, and the molar ratio of oxalic acid to total nitrate radical is 1.0:1) into the reaction kettle at one time; the evaporated water was collected by condensation to 1230mL and stirring was stopped to yield 174g of a gel. The resulting gel was placed in an enamel plate and dried at 120 ℃ for 12 hours, and the dried solid was calcined at 350 ℃ for 4 hours to obtain a total of 34.9g of black powder H (metal ion yield 99.6%). And tabletting the black powder H by adopting a tabletting forming mode, wherein the tabletting pressure is 7.0MPa, and thus the catalyst H is obtained.

The comparative example is different from example 2 in the way of adding the oxalic acid solution, and since oxalic acid is gradually decomposed to generate gas as the reaction proceeds, the volume of the reaction chamber required in example 2 and the comparative example is slightly different, but the difference in volume does not constitute a substantial influence.

Comparative example 4

Respectively measuring 241.98mL of copper nitrate solution (with the concentration of 1.0mol/L) and 207.25mL of chromium nitrate solution (with the concentration of 1.0mol/L), and placing the solutions in a glass reaction kettle with a clamp sleeve and the volume of which is 600mL, wherein the mass ratio of copper to chromium is 1.17: 1; starting stirring and introducing heat conducting oil, and controlling the temperature in the reaction kettle to be 80 ℃; adding 369mL of total amount 1107mL of oxalic acid solution (the concentration is 1.0mol/L, and the molar ratio of oxalic acid to total nitrate radical is 1.0:1) into the reaction kettle for three times at intervals of 1 hour; the evaporated water was collected by condensation to 1230mL and stirring was stopped to yield 174g of a gel. The resulting gel was placed in an enamel plate and dried at 120 ℃ for 12 hours, and the dried solid was calcined at 350 ℃ for 4 hours to obtain a total of 34.9g of black powder I (metal ion yield 99.6%). And tabletting the black powder I by adopting a tabletting forming mode, wherein the tabletting pressure is 7.0MPa, and thus obtaining the catalyst I.

This comparative example differs from example 2 in the manner of addition of the oxalic acid solution.

Secondly, analyzing the physical and chemical properties of the catalyst

The catalyst powder obtained by the preparation was subjected to XRD and BET analysis tests.

The XRD test results are shown in fig. 2. Catalyst A was prepared as described in example 1, using a mixed solution of copper nitrate and chromium nitrate to which oxalic acid was added in a molar amount equivalent to the total NO₃ ^-And oxalic acid aqueous solution with the molar weight of 1.1 times is obtained by evaporation and hydrolysis. Catalysts D and C are comparative example 1 and example 3, respectively, and the raw material ratio and preparation method of catalyst D are identical to those of catalyst A except that oxalic acid is not added dropwise during the preparation of catalyst D, and the amount of oxalic acid added during the preparation of catalyst C is about half of that of A.

Comparing the XRD spectrum of catalyst A, D, C, only three characteristic diffraction peaks of copper oxide were found in the spectrum of catalyst A, and CuCrO was also found in the spectrum of catalysts D and C in addition to the diffraction peaks of copper oxide₄And a spinel-form copper-chromium composite oxide.

The chemical reaction research on the evaporation hydrolysis process of the copper nitrate and chromium nitrate mixed solution in the early stage finds that: under the evaporation condition, trivalent chromium ions are oxidized into hexavalent chromium ions by nitrate ions due to the existence of nitrate ions in the reaction system. This indicates the presence of the edge of the copper chromate diffraction peak in the XRD spectrum of catalyst D. Based on the knowledge, the invention creatively provides that oxalic acid is added in the evaporation hydrolysis process of the mixed solution of copper nitrate and chromium nitrate, and the oxalic acid is utilized to play a role in reduction, thereby effectively relieving the problem that trivalent chromium ions are oxidized into hexavalent chromium ions. Comparing the phase result of catalyst A, C, D, the oxidation degree of trivalent chromium ion gradually decreases with the increase of oxalic acid addition, and the XRD spectrogram is attributed to CuCrO₄Diffraction of spinel-form copper-chromium composite oxideThe peak is reduced or disappeared, further confirming the rationality of the preparation method of the present invention.

Catalyst E was prepared using the conventional co-current co-precipitation method described in comparative example 2. From the metal ion yield data, the catalyst prepared by the evaporation hydrolysis method of the invention has a metal ion yield of more than 99%. In particular, the production process according to the invention substantially eliminates the discharge of metal ion-containing waste water. While the yield of metal ions in the co-precipitation method of comparative example 2 was only about 90%, which is significantly lower than that of the evaporation hydrolysis method. The co-precipitation method has a large loss of metal ions, so that not only the manufacturing cost of the catalyst is increased, but also a large amount of waste water containing metal ions and nitrates is discharged. Especially, the waste water containing high-valence chromium ions is generated, and hidden troubles exist for the environment and the personal safety of production personnel.

Comparing the XRD patterns of catalysts E and A, D, C, it can be seen that the copper oxide diffraction peak of catalyst E is higher and larger than that of the catalysts prepared by the evaporative hydrolysis method (especially catalysts a and C prepared by adding oxalic acid), indicating that the copper oxide grains of the catalysts obtained by the evaporative hydrolysis method (e.g., catalyst a, catalyst C) are smaller than those of the coprecipitation method. This is advantageous for improving the hydrogenation activity and selectivity of the catalyst.

The BET test results are shown in table 1.

Table 1: physicochemical Property analysis results of catalyst

Comparing the analysis data of catalyst A, E, D, C, it can be seen that catalysts A and B obtained by reductive evaporation hydrolysis using a mixed solution of copper nitrate and chromium nitrate have the largest specific surface area and pore volume, which indicates that the obtained catalysts have copper oxide and chromium oxide dispersed relatively uniformly and have smaller particle sizes, which is consistent with the analysis result of XRD.

Therefore, the catalyst obtained by the reduction evaporation hydrolysis method of the mixed solution of the copper nitrate and the chromium nitrate has large specific surface area (not less than 50 m)²Per gram), large pore volume (not less than 0.3 cm)³Per gram) and a proper pore diameter (15 nm-17 nm), and the phase composition is amorphous chromium oxide loaded small-grain copper oxide.

Third, evaluation of catalyst Performance

With technical enals or aldehydes (purity)>98 wt.%) was used as a raw material, and the catalysts of the above examples and comparative examples were evaluated for hydrogenation performance in a fixed bed reactor having a catalyst loading of 10 g. The process conditions for all evaluation reactions were the same and were: the space velocity of the feeding volume is 0.3h^-1The reaction pressure is 3.0MPa, the reaction temperature is 160 ℃, and the molar ratio of the reaction hydrogen to the olefine aldehyde or aldehyde is 10; sampling analysis was started 10 hours after the reaction operation was stable. Samples were taken every hour, 10 consecutive samples were taken for chromatographic analysis, and the results were arithmetically averaged, more specifically:

the raw material was 2-Propylheptenal (PBA) with a purity of 99.85 wt%, and the results of the catalyst hydrogenation performance evaluation are shown in Table 2.

The starting material was trans-2-heptanal (EPA) with a purity of 99.7 wt%, and the results of the catalyst hydrogenation performance evaluation are shown in Table 3.

The n-butyraldehyde was used as the starting material, the purity was 99.5 wt%, and the results of the evaluation of the hydrogenation performance of the catalyst are shown in Table 4.

Isobutyraldehyde was used as a raw material, the purity was 98.9 wt%, and the results of the evaluation of the hydrogenation performance of the catalyst are shown in Table 5.

Isononanal is used as a raw material, the purity is 98.5 wt%, the heavy component content is 0.02 wt%, and the hydrogenation performance evaluation result of the catalyst is shown in table 6.

The raw materials adopt C11-C17 mixed aldehyde^②The purity was 98.6 wt%, the heavy component content was 0.05 wt%, and the results of the evaluation of the hydrogenation performance of the catalyst are shown in Table 7.

TABLE 2

Table 2 lists the hydrogenation performance evaluation data for different catalysts using the same raw PBA under the same process conditions. The data in the table show that the catalyst prepared by reduction, evaporation and hydrolysis of the mixed solution of copper nitrate and chromium nitrate has higher hydrogenation activity and selectivity to target products, and can even approach or reach 100%.

Comparative example 2 catalyst E was prepared using a conventional co-current co-precipitation process. The PBA content is high, and the conversion rate and the selectivity are inferior to the performance of the catalyst prepared by the evaporation hydrolysis method provided by the invention.

TABLE 3

Table 3 shows the data for the evaluation of hydrogenation performance of different catalysts using the same EPA as the feedstock under the same process conditions. The data in the table show that the catalyst prepared by reduction, evaporation and hydrolysis of the mixed solution of copper nitrate and chromium nitrate has higher hydrogenation activity and selectivity to target products, and can even approach or reach 100%.

Comparative example 2 catalyst E was prepared using a conventional co-current co-precipitation process. The catalyst has high EPA content, and the conversion rate and the selectivity are inferior to the performance of the catalyst prepared by the evaporation hydrolysis method provided by the invention.

TABLE 4

Table 4 shows the data of the evaluation of the hydrogenation performance of different catalysts using the same raw material, n-butyraldehyde, under the same process conditions. The data in the table show that the catalyst prepared by reduction, evaporation and hydrolysis of the mixed solution of copper nitrate and chromium nitrate has higher hydrogenation activity and selectivity to target products, and can even approach or reach 100%.

TABLE 5

Table 5 shows the data of the evaluation of hydrogenation performance of different catalysts using the same raw material isobutyraldehyde under the same process conditions. The data in the table show that the catalyst prepared by reduction, evaporation and hydrolysis of the mixed solution of copper nitrate and chromium nitrate has higher hydrogenation activity and selectivity to target products, and can even approach or reach 100%.

Comparative example 2 catalyst E was prepared using a conventional co-current co-precipitation process. The content of isobutyraldehyde is high, and the conversion rate and the selectivity are both inferior to the performance of the catalyst prepared by the evaporation hydrolysis method provided by the invention.

TABLE 6

Note: the heavy component is shown in the formula I.

Table 6 shows the evaluation data of hydrogenation performance of different catalysts using the same raw material isononanal under the same process conditions. The data in the table show that the catalyst prepared by reducing, evaporating and hydrolyzing the mixed solution of copper nitrate and chromium nitrate has higher hydrogenation activity and selectivity to target products, and even can approach 100%.

Comparative example 2 catalyst E was prepared using a conventional co-current co-precipitation process. The isononanal content is high, and the conversion rate and selectivity are inferior to the performance of the catalyst prepared by the evaporation hydrolysis method provided by the invention.

TABLE 7

Note: the first step is heavy components;

② C11-C17 mixed aldehyde is prepared by hydroformylation of C10-C16 terminal olefin, the aldehyde composition is: 22.2% of C11 aldehyde, 24.35% of C13 aldehyde, 32.24% of C15 aldehyde and 19.82% of C17 aldehyde.

Table 7 shows the evaluation data of hydrogenation performance of different catalysts using the same raw material C11-C17 mixed aldehyde under the same process conditions. The data in the table show that the catalyst prepared by reducing, evaporating and hydrolyzing the mixed solution of copper nitrate and chromium nitrate has higher hydrogenation activity and selectivity to target products, and even can approach 100%.

The applicant states that the present invention is illustrated in detail by the above examples, but the present invention is not limited to the above detailed methods, i.e. it is not meant that the present invention must rely on the above detailed methods for its implementation. It should be understood by those skilled in the art that any modification of the present invention, equivalent substitutions of the raw materials of the product of the present invention, addition of auxiliary components, selection of specific modes, etc., are within the scope and disclosure of the present invention.

Claims

1. a preparation method of copper-chromium catalyst, is characterized in that, described method may further comprise the steps:

An aqueous solution containing copper salt and chromium salt is provided as a reaction solution, heated and gelled to obtain a precursor;

Wherein, the anion in the copper salt and/or the chromium salt contains nitrate, and the reaction solution contains an additive, and the additive is a reducing substance and/or can be decomposed to generate a reducing substance during the heating gelation process. raw material;

The precursor is dried and calcined to obtain a copper-chromium catalyst.

2. The method according to claim 1, wherein the cation of the copper salt in the reaction solution is Cu ²⁺ , the cation of the chromium salt is Cr ³⁺ , and the molar ratio of the Cu ²⁺ and Cr ³⁺ It is 0.6:1 to 1.5:1, preferably 0.9:1 to 1.45:1;

Preferably, the additive comprises any one or a combination of at least two of copper oxalate, oxalic acid, ammonium bicarbonate, ammonium oxalate or aqueous ammonia, preferably any one of oxalic acid, ammonium bicarbonate, ammonium oxalate or aqueous ammonia or A combination of at least two; preferably, the reaction solution is prepared by the following method: mixing a copper salt solution and a chromium salt solution to obtain a metal salt solution, and then adding an additive to the metal salt solution, the additive is a reducing aqueous solution;

Preferably, the concentrations of the copper salt solution and the chromium salt solution are independently 0.5 mol/L to 2 mol/L; or base;

Preferably, the reducing aqueous solution comprises any one or a mixture of at least two of ammonium bicarbonate aqueous solution, ammonium oxalate aqueous solution, oxalic acid or ammonia water;

Preferably, the concentration of the reducing aqueous solution is 0.5mol/L～2mol/L;

Preferably, the added amount of the reducing aqueous solution satisfies: the molar ratio of the total amount of the added ammonium ions and/or oxalate ions to the NO ₃ contained in the reaction solution ^— is 1:1 to 1.1:1 .

3. The method according to claim 1 or 2, wherein the thermal gelation process is accompanied by the continuous addition of additives;

Preferably, the preparation method of the precursor comprises the following steps:

Mix the copper salt solution and the chromium salt solution to obtain a metal salt solution, heat to a certain temperature, and continue to add additives until a gel is obtained;

Preferably, the heating to a certain temperature is heating to 80°C to 95°C;

Preferably, the continuous addition is accompanied by stirring;

Preferably, the gas-phase substances produced during the thermal gelation are transferred out of the reaction chamber;

Preferably, the volume of the liquid water obtained by condensation of the transferred gas-phase substance accounts for 70%-95% of the total volume of the reaction solution, preferably 75%-90%.

4. The method according to any one of claims 1-3, wherein the temperature for drying the precursor is 80°C to 140°C;

Preferably, the temperature for calcining the precursor is 300°C to 400°C.

5. The method according to any one of claims 1-4, characterized in that, the method further comprises molding the calcined product.

6. The method according to any one of claims 1-5, wherein the method comprises the following steps:

An aqueous solution containing copper nitrate and chromium nitrate is provided as a pre-reaction solution;

heating the reaction solution to 80°C to 95°C, continuously adding a reducing aqueous solution to the pre-reaction solution under stirring until a gel is obtained, drying and calcining the gel to obtain a copper-chromium catalyst;

The gas-phase substances produced by the heating reaction are transferred out of the reaction chamber in real time;

Wherein, the reducing aqueous solution is selected from any one or at least two mixtures of ammonium bicarbonate aqueous solution, ammonium oxalate aqueous solution, oxalic acid or ammonia water; the addition amount of the reducing aqueous solution satisfies the added ammonium ion, oxalate radical ^The molar ratio of the amount of its total substance and the nitrate NO ₃ contained in the reaction solution is 0.9:1 to 1.5:1.

7. A copper-chromium catalyst prepared according to any one of claims 1-6, wherein the copper-chromium catalyst comprises CuO and Cr ₂ O ₃ ;

Preferably, the copper element in the copper-chromium catalyst exists in the form of CuO, and the BET specific surface area of the copper-chromium catalyst is greater than or equal to 50 m ² /g.

8 . The copper-chromium catalyst according to claim 7 , wherein the mass ratio of the CuO and Cr ₂ O ₃ is 40:60 to 60:40; 8 .

Preferably, the pore volume of the copper-chromium catalyst is greater than or equal to 0.3 cm ³ /g;

Preferably, the average pore size of the copper-chromium catalyst is 14 nm˜17 nm.

9. A method for preparing alkanol by hydrogenation of alkenal or aldehyde, wherein the method adopts the copper-chromium catalyst according to claim 7 or 8.

10. The method according to claim 9, wherein the alkenal comprises any one or a combination of both of 2-propyl-2-heptenal and 2-ethylhexenal;

Preferably, the aldehyde comprises any one or a combination of at least two of isobutyraldehyde, n-butyraldehyde or isononanal;

Preferably, in the method, the conditions for hydrogenation catalysis are: the molar ratio of hydrogen to alkenal or aldehyde is 2-20; the reaction temperature is 140°C-200°C; the reaction pressure is 2MPa-5MPa; the feed volume space velocity is 0.1h ^-1 to 1h ^-1 .