Hydrogenation catalyst and preparation method thereof
By introducing ammonia vaporization method and water vapor etching method into the traditional hydrogenation catalyst preparation method, the problems of insufficient activity and selectivity and low stability in the traditional methods are solved, and a more efficient and stable preparation of hydrogenation catalyst is achieved.
Patent Information
- Application Number
- CN202411546325.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-10-31
- Publication Date
- 2025-02-25
AI Technical Summary
The traditional hydrogenation catalyst preparation method has problems such as insufficient activity and selectivity, low stability and complex preparation process, resulting in unsatisfactory activity and selectivity of the catalyst and short service life.
The metal element is attached to the catalyst support by ammonia vaporization method, and the catalyst precursor is obtained by oxidation, and the catalyst precursor is reduced in a hydrogen environment by water vapor etching to obtain a hydrogenation catalyst.
Through water vapor etching treatment, the dispersion of the active metal is regulated, unstable structures and impurities are removed, the catalyst's anti-sintering ability is enhanced, the catalyst's activity, selectivity and stability are improved, and the preparation process is simplified.
Smart Images
Figure CN119500127A_ABST
Abstract
Description
Technical Field
[0001] The present application relates to the field of catalyst technology, and in particular to a hydrogenation catalyst and a preparation method thereof. Background Art
[0002] In modern industry, hydrogenation reactions are widely used in the fields of petroleum refining, chemical synthesis, etc. Hydrogenation catalysts can accelerate the hydrogenation reaction, improve the reaction efficiency and selectivity, and play a vital role in the production of clean fuels, high value-added chemicals, etc. For example, in petroleum refining, hydrogenation can remove impurities such as sulfur, nitrogen, and oxygen in oil products and improve the quality of oil products; in chemical synthesis, hydrogenation reactions can synthesize various important organic compounds.
[0003] Traditional methods for preparing hydrogenation catalysts mainly include impregnation, ion exchange, co-precipitation, etc. Although these methods can prepare catalysts with certain activity and selectivity to a certain extent, they also have some limitations, including the need to improve activity and selectivity, insufficient stability, and complex preparation process. Among them, the catalysts prepared by traditional methods may have problems such as uneven distribution of active sites and unreasonable pore structure, resulting in less than ideal activity and selectivity of the catalyst. In addition, during long-term use, traditional catalysts are prone to carbon deposition and loss of active components, thereby reducing the stability and service life of the catalyst. At the same time, some traditional methods require complex process steps and strict reaction conditions, which increases the cost and difficulty of preparation. Summary of the invention
[0004] The present application aims to solve at least one of the technical problems in the related art to a certain extent. The present application firstly uses the ammonia evaporation method to attach metal elements to the catalyst carrier respectively, and oxidizes the metal elements on the catalyst carrier to obtain a catalyst precursor, and then uses the water vapor etching method to etch the catalyst precursor in the reactor while reducing it with hydrogen, so as to obtain the desired hydrogenation catalyst, which overcomes the technical difficulty that the etching catalyst in the related art needs to be refilled and reduced, and simplifies the complexity and limitations of the hydrogenation catalyst preparation method.
[0005] On the one hand, the present application proposes a method for preparing a hydrogenation catalyst, comprising the following steps:
[0006] Utilizing metal elements to attach to a catalyst carrier, and oxidizing the metal elements on the catalyst carrier to obtain a catalyst precursor;
[0007] The catalyst precursor is placed in a reactor at a temperature of 60-200° C., and reduced for 2-48 hours under the conditions of a pressure of 0.5-5 MPa, a hydrogen flow rate of 100-600 ml / min, and a water vapor inlet of 0.01-0.1 ml / min to obtain a hydrogenation catalyst.
[0008] In some embodiments, the method for preparing the catalyst precursor comprises:
[0009] The catalyst carrier is added into a mixed solution A formed by a metal nitrate solution and ammonia water in a certain proportion, and stirred to obtain a mixed solution B;
[0010] The mixed solution B is continuously heated and stirred for a certain period of time to obtain a mixed solution C; the precipitate obtained after filtering the mixed solution C is dried and calcined.
[0011] In some embodiments, the metal nitrate includes at least one of nickel nitrate, silver nitrate, copper nitrate, etc.; based on the catalyst, the content of the metal element is 0.1-30wt%.
[0012] In some embodiments, the catalyst support includes at least one of alumina, silica, activated carbon, or molecular sieves.
[0013] In some embodiments, the mixed solution B is continuously heated in an oil bath at a temperature of 80-150° C.; the precipitate obtained after filtering the mixed solution C is dried at a temperature of 80-150° C. and calcined at a temperature of 200-800° C. for 2-12 hours.
[0014] In some embodiments, the volume ratio of the metal nitrate solution to ammonia water is 1-5:1; the concentration of the metal nitrate solution is 1wt%-30wt%.
[0015] In some embodiments, the mass ratio of the catalyst carrier to the mixed liquid A is 1:3-9.
[0016] On the other hand, the present application provides a hydrogenation catalyst obtained by the preparation method described in any of the above embodiments.
[0017] In some embodiments, the catalyst comprises an active metal component and a support, and the catalyst is subjected to a water vapor etching treatment.
[0018] In another aspect, the present application proposes the use of the hydrogenation catalyst described in any of the above embodiments in the hydrogenation reaction of dimethyl oxalate.
[0019] Compared with the related art, this application has the following beneficial effects:
[0020] (1) Regulating the dispersion of active metals: Water vapor etching may affect the dispersion of active metals on the catalyst. Through appropriate etching conditions, the active metals can be more evenly distributed on the catalyst surface, thereby improving the utilization of active centers.
[0021] (2) After the catalyst is etched by water vapor, the amount of precious metal added in the catalyst can be replaced. For example, the copper catalyst can replace metal gold or silver, and the performance in the catalytic hydrogenation reaction is completely different from that of traditional copper catalysts, but close to that of gold and silver;
[0022] (3) Removal of unstable structures and impurities: During the hydrogenation reaction, unstable structures and impurities on the catalyst surface can easily reduce the activity of the catalyst. Water vapor etching can remove these adverse effects to a certain extent.
[0023] (4) Enhance the anti-sintering ability of the catalyst: Under high temperature reaction conditions, the active metal in the catalyst is prone to sintering, resulting in catalyst deactivation. Water vapor etching can form a stable oxide layer on the catalyst surface, inhibiting the sintering of the active metal and improving the stability of the catalyst;
[0024] (5) The water vapor etching treatment method in the present application is simple. Compared with the catalyst etched by water vapor treatment in a muffle furnace, the refilling and reduction process can be omitted, and it is easier to realize industrial production.
[0025] Therefore, the appropriate etching conditions in this application, i.e., the pressure is 0.5-5MPa, the hydrogen flow rate is 100-600ml / min, and the water vapor inlet is 0.01-0.1ml / min, and the reduction is carried out for 2-48h, which can make the active metal more evenly distributed on the catalyst surface, which is beneficial to increase the pore volume and pore diameter of the catalyst, improve the utilization rate of the active center and the selectivity of the target product; at the same time, water vapor etching can remove the adverse effects of unstable catalyst structure and impurities to a certain extent; in addition, a stable oxide layer can be formed on the catalyst surface to inhibit the sintering of active metals and improve the stability of the catalyst. The main principle is that water vapor reacts with the substances on the catalyst surface at high temperature, etches away some impurities and unstable structures, and adjusts the pore structure and surface chemical properties of the catalyst, thereby improving the activity, selectivity and stability of the catalyst.
[0026] Additional aspects and advantages of the present application will be given in part in the description below, and in part will become apparent from the description below, or will be learned through the practice of the present application. BRIEF DESCRIPTION OF THE DRAWINGS
[0027] The above and / or additional aspects and advantages of the present application will become apparent and easily understood from the following description of the embodiments in conjunction with the accompanying drawings, in which:
[0028] Figure 1 It is a flow chart of a method for preparing a hydrogenation catalyst according to an embodiment of the present application. DETAILED DESCRIPTION
[0029] Embodiments of the present application are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements with the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present application, and cannot be construed as limiting the present application. On the contrary, the present application includes all changes, modifications and equivalents that fall within the spirit and connotation of the appended claims.
[0030] On the one hand, the present application proposes a method for preparing a hydrogenation catalyst, comprising the following steps:
[0031] S1: using metal elements to attach to a catalyst carrier and oxidizing the metal elements on the catalyst carrier to obtain a catalyst precursor;
[0032] S2: placing the catalyst precursor in a reactor at a temperature of 60-200°C, and reducing it for 2-48h under the conditions of a pressure of 0.5-5MPa, a hydrogen flow rate of 100-600ml / min, and a water vapor inlet of 0.01-0.1ml / min to obtain a hydrogenation catalyst.
[0033] Among them, the metal nitrate solution and ammonia water in S1 form a mixed solution A in proportion, wherein the metal nitrate includes at least one of nickel nitrate, silver nitrate, and copper nitrate, and the concentration of the metal nitrate solution is 1wt%-30wt%, for example, the concentration of the nitrate solution is 1wt%, 5wt%, 10wt%, 15wt%, 20wt%, 25wt%, 30wt%; wherein the content of the metal element is 0-30wt% based on the catalyst, that is, the percentage of the gram weight of the metal element to the amount of the catalyst (the weight after calcination to remove water), for example, the content of the metal element is 0.1wt%, 1wt%, 5wt%, 10wt%, 15wt%, 20wt%, 25wt%, 30wt%.
[0034] In this embodiment, the volume ratio of the metal nitrate solution to the ammonia water is 1-5:1, for example, the volume ratio of the metal nitrate solution to the ammonia water is (1, 2, 3, 4, 5):1, etc. When the amount of metal element added is too high, too much metal may promote excessive hydrogenation reaction, generate unwanted by-products, and reduce the selectivity of the target product.
[0035] Add the catalyst carrier to the mixed liquid A and stir to obtain the mixed liquid B; wherein the catalyst carrier includes at least one of aluminum oxide, silicon oxide, activated carbon or molecular sieve; the mass ratio of the catalyst carrier to the mixed liquid A is 1:3-9, for example, the mass ratio of the catalyst carrier to the mixed liquid A is 1:(3, 4, 5, 6, 7, 8, 9), etc.
[0036] Mixed liquid B is continuously heated in an oil bath at a temperature of 80-150°C for 6-24 hours; the precipitate obtained after filtering mixed liquid C is dried at a temperature of 80-150°C, and calcined at a temperature of 200-800°C for 2-12 hours to obtain a catalyst precursor. The mixed liquid B is heated in the oil bath at a temperature of 80°C, 90°C, 100°C, 110°C, 120°C, 130°C, 140°C, 150°C, etc., and the heating time is 2h, 3h, 4h, 5h, 6h, 7h, 8h, etc. When the mixed liquid B is not heated in the oil bath for a long time, this will lead to insufficient ammonia evaporation process, affecting the activity of the catalyst and the selectivity of the target product; while a high heating temperature has little effect, but a too low heating temperature affects the efficiency of the ammonia evaporation process.
[0037] In this embodiment, the precipitate obtained after filtering the mixed solution C is dried at a temperature of 80-150°C, and the drying temperature can be 80°C, 90°C, 100°C, 110°C, 120°C, 130°C, 140°C, 150°C, etc. The dried precipitate can be calcined at a temperature of 200°C, 300°C, 400°C, 500°C, 600°C, 700°C, 800°C, etc., and the calcination time is 2h, 3h, 4h, 5h, 6h, 7h, 8h, 9h, 10h, 11h, 12h, etc.
[0038] In S2, the catalyst precursor is placed in a reactor at a temperature of 60-200°C, and reduced for 2-48 hours under the conditions of a pressure of 0.5-5MPa, a hydrogen flow rate of 100-600ml / min, and a water vapor inlet of 0.01-0.1ml / min to obtain a hydrogenation catalyst.
[0039] For example, the temperature at which the catalyst precursor is placed in the reactor may be 60°C, 70°C, 80°C, 90°C, 100°C, 110°C, 120°C, 130°C, 140°C, 150°C, 160°C, 170°C, 180°C, 190°C, 200°C, etc.; the temperature at which the precursor is placed in the reactor is the reduction temperature of the ordinary unetched catalyst; when the temperature is too low, such as below 60°C, the degree of reduction of the catalyst is insufficient, and the active sites cannot be fully exposed and activated. This will greatly reduce the catalytic ability of the catalyst in the reaction and significantly reduce the reaction rate. When the temperature is too high, such as above 200°C, it is easy to cause sintering and aggregation of the catalyst. High temperature will cause the catalyst particles to fuse with each other, reduce the specific surface area, reduce the number of active sites, and cause the catalyst to lose its original catalytic function.
[0040] In this embodiment, the pressure of the reactor can be 0.5MPa, 1MPa, 2MPa, 3MPa, 4MPa, 5MPa, etc. When the pressure of the reactor is low, such as lower than 0.5MPa, the concentration of water vapor molecules is relatively low, and the frequency of collision with the catalyst surface is reduced. This will cause the etching rate to slow down, and the degree of etching on the catalyst surface will be relatively light; when the pressure of the reactor is high, such as higher than 5MPa, the concentration of water vapor molecules increases, and the frequency of collision with the catalyst surface is greatly increased. This will accelerate the etching process and significantly increase the etching rate. At the same time, an excessively high etching rate may make the etching process difficult to control, prone to over-etching, and the catalyst pore structure collapses, which has an adverse effect on the performance of the catalyst.
[0041] The hydrogen flow rate introduced in the present embodiment is 100ml / min, 200ml / min, 300ml / min, 400ml / min, 500ml / min, 600ml / min. When the hydrogen flow rate is small, such as less than 100ml / min, the reduction process has little effect on the structure of the catalyst. This helps to maintain the original structure and morphology of the catalyst and improve the stability of the catalyst. However, incomplete reduction under a lower hydrogen flow rate may cause the performance of the catalyst to gradually decline during subsequent use. However, when the hydrogen flow rate is large, such as greater than 600ml / min, the rapid reduction process may have a certain impact on the structure of the catalyst. If improperly controlled, it may cause the pore structure of the catalyst to collapse, the active component to agglomerate or the carrier to be damaged, thereby reducing the stability of the catalyst.
[0042] In this embodiment, the water vapor inlet is 0.01ml / min, 0.02ml / min, 0.03ml / min, 0.04ml / min, 0.05ml / min, 0.06ml / min, 0.07ml / min, 0.08ml / min, 0.1ml / min, etc. When the water vapor inlet is low, such as less than 0.01ml / min, the contact between water vapor and the catalyst is relatively small, the etching of the catalyst precursor is insufficient, and the effect on the catalyst activity may be relatively limited. When the water vapor inlet is high, such as higher than 0.1ml / min, the excessive water vapor inlet will hinder the contact between the reducing gas and the catalyst, significantly reducing the reduction rate. Water vapor will occupy a large number of active sites on the catalyst surface, making it difficult for the reducing gas to adsorb and react.
[0043] In the present embodiment, the reduction time is 2h, 4h, 10h, 15h, 20h, 24h, 30h, 35h, 40h, 48h, etc. When the time is short, such as shorter than 2h, the catalyst may not be fully reduced, and the active site fails to be fully formed. This will result in a lower activity of the catalyst, showing a slower reaction rate and a lower conversion rate in the catalytic reaction. When the reduction time is long, such as longer than 48h, the sintering of the catalyst may be caused, the particles of the catalyst become larger, the specific surface area is reduced, and the active sites are reduced, thereby reducing the activity of the catalyst.
[0044] On the other hand, the present application provides a hydrogenation catalyst obtained by using the preparation method in any of the above embodiments.
[0045] In some embodiments, the catalyst includes an active metal component and a carrier, and is treated with water vapor etching so that the catalyst has a specific pore structure and activity distribution to improve the hydrogenation reaction performance.
[0046] In another aspect, the present application proposes the use of the hydrogenation catalyst in any of the above embodiments in the hydrogenation reaction of dimethyl oxalate.
[0047] The present application will be described in detail below with reference to embodiments.
[0048] Example 1
[0049] 38 g of copper nitrate was placed in 400 ml of deionized water, stirred evenly, and then 400 g of ammonia water was added and stirred thoroughly to obtain a mixed solution A. 133.3 g of silica sol was added to the mixed solution A and stirred for 30 min to obtain a mixed solution B. The mixed solution B was placed in an oil bath at 80° C. and continuously heated and stirred for 8 h to obtain a mixed solution C. The mixed solution C was repeatedly filtered and centrifuged in a centrifuge for 2-4 times to obtain a precipitate. The precipitate was dried in an oven at 90° C. for 12 h, and calcined in a muffle furnace at 600° C. for 12 h to obtain a catalyst precursor.
[0050] The catalyst precursor is loaded into the reactor, which is first preheated to 100°C, and then etched for 5 hours at a system pressure of 1.5 MPa, accompanied by a hydrogen flow rate of 150 ml / min and a water vapor inlet of 0.05 ml / min, to obtain a hydrogenation catalyst after water vapor etching.
[0051] Example 2
[0052] The present embodiment differs from the embodiment 1 in that the nitrate components added to the deionized water in step 1 are 74.3 g of nickel nitrate and 28.5 g of copper nitrate, and the other steps and conditions remain the same.
[0053] Example 3
[0054] The present embodiment differs from the embodiment 1 in that the nitrate components added to the deionized water in step 1 are 7.87 g of silver nitrate and 24.77 g of nickel nitrate, and the other steps and conditions remain the same.
[0055] Example 4
[0056] The present embodiment differs from the embodiment 1 in that the nitrate component added to the deionized water in step 1 is 49.54 g of nickel nitrate, and the other steps and conditions remain the same.
[0057] Example 5
[0058] The difference between this comparison and Example 2 is that the etching time is 20 hours, and the other steps and conditions remain the same.
[0059] Example 6
[0060] The difference between this comparison and Example 4 is that the system pressure of the reduction etching process is 1.5 MPa, and the other steps and conditions remain the same.
[0061] Example 7
[0062] The difference between this comparison and Example 4 is that the system pressure of the reduction etching process is 2.5 MPa, and the other steps and conditions remain the same.
[0063] Example 8
[0064] The difference between this comparison and Example 4 is that the system pressure of the reduction etching process is 5 MPa, and the other steps and conditions remain the same.
[0065] Comparative Example 1
[0066] The difference between this comparative example and Example 1 is that the catalyst precursor F prepared in step 2 is not subjected to water vapor etching treatment, and other steps and conditions remain the same.
[0067] Comparative Example 3
[0068] The difference between this comparison and Example 3 is that the water vapor inlet rate is 1 ml / min, and the other steps and conditions remain the same.
[0069] The catalyst samples of each embodiment and comparative example were evaluated under uniform hydrogenation reaction conditions for 100 hours. The results are shown in Table 1.
[0070] Table 1 Catalyst sample evaluation results
[0071] sample Raw material conversion rate / % Selectivity of target product / % Example 1 99.28 80.81 Example 2 99.52 79.45 Example 3 98.15 80.17 Example 4 97.52 78.36 Example 5 99.83 85.00 Example 6 98.78 80.53 Example 7 99.98 85.45 Example 8 95.87 79.26 Comparative Example 1 90.35 74.48 Comparative Example 3 98.74 76.53
[0072] According to the analysis of the catalyst sample evaluation results in Table 1, the target product selectivity and raw material conversion rate of Comparative Example 1 are both reduced to a certain extent compared with Example 1, indicating that water vapor etching will affect the dispersion of metal elements on the catalyst surface and the catalyst surface structure, thereby affecting the raw material conversion rate, target product selectivity and other aspects. Compared with Example 2, Example 5 significantly improves the selectivity of the target product, indicating that the duration of the etching process has an impact on the treatment of the catalyst, and the relatively long water vapor etching time promotes the dredging of the catalyst structure and the increase of pore volume and pore size. Compared with Example 3, the selectivity of the target product of Comparative Example 3 shows a downward trend, which may be due to the excessive water vapor introduced during the etching process, which is not conducive to the catalyst reduction reaction, and there is also the possibility that the catalyst particles become coarser and the surface area is reduced. Compared with Example 4, the raw material conversion rate and target product selectivity of Example 6 and Example 8 show an increasing trend. The higher pressure during the etching process will prompt water vapor to enter the pores of the catalyst more forcefully, which may enlarge the pores with small pore sizes or create connections between originally independent pores, thereby increasing the specific surface area and porosity of the catalyst and increasing the number of active sites of the catalyst. The raw material conversion rate and target product selectivity of Example 8 decreased, which may be due to excessive etching pressure, resulting in the collapse of the pore structure of the catalyst or excessive etching, which in turn reduced the specific surface area and the number of active sites, thereby reducing the catalytic activity.
[0073] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.
[0074] Although the embodiments of the present application have been shown and described above, it can be understood that the above embodiments are exemplary and cannot be understood as limitations on the present application. Ordinary technicians in this field can change, modify, replace and modify the above embodiments within the scope of the present application.
Claims
1. A method for preparing a hydrogenation catalyst, characterized in that: The following steps are involved: Utilizing metal elements to attach to a catalyst carrier, and oxidizing the metal elements on the catalyst carrier to obtain a catalyst precursor; The catalyst precursor is placed in a reactor at a temperature of 60-200° C., and reduced for 2-48 hours under the conditions of a pressure of 0.5-5 MPa, a hydrogen flow rate of 100-600 ml / min, and a water vapor inlet of 0.01-0.1 ml / min to obtain a hydrogenation catalyst.
2. The preparation method according to claim 1, characterized in that: The preparation method of the catalyst precursor comprises: The catalyst carrier is added into a mixed solution A formed by a metal nitrate solution and ammonia water in a certain proportion, and stirred to obtain a mixed solution B; The mixed solution B is continuously heated and stirred for a certain period of time to obtain a mixed solution C; the precipitate obtained after filtering the mixed solution C is dried and calcined.
3. The preparation method according to claim 2, characterized in that: The metal nitrate includes at least one of nickel nitrate, silver nitrate and copper nitrate; based on the catalyst, the content of the metal element is 0.1-30wt%.
4. The preparation method according to claim 2, characterized in that: The catalyst carrier includes at least one of aluminum oxide, silicon oxide, activated carbon or molecular sieve.
5. The preparation method according to claim 2, characterized in that: The mixed solution B is continuously heated in an oil bath at a temperature of 80-150° C.; the precipitate obtained after filtering the mixed solution C is dried at a temperature of 80-150° C. and calcined at a temperature of 200-800° C. for 2-12 hours.
6. The preparation method according to claim 1, characterized in that: The volume ratio of the metal nitrate solution to ammonia water is 1-5:1; the concentration of the metal nitrate solution is 1wt%-30wt%.
7. The preparation method according to claim 1 or 6, characterized in that: The mass ratio of the catalyst carrier to the mixed liquid A is 1:3-9.
8. A hydrogenation catalyst, characterized in that The method is obtained by any one of claims 1 to 7.
9. The hydrogenation catalyst according to claim 8, characterized in that The catalyst comprises an active metal component and a carrier, and the catalyst is treated by water vapor etching.
10. Use of the hydrogenation catalyst according to claim 8 or 9 in the hydrogenation reaction of dimethyl oxalate.