Preparation method of copper-based bimetallic catalyst, copper-based catalyst and application

Abstract

The application discloses a preparation method of a copper-based bimetallic catalyst, the copper-based catalyst and application, and the preparation method comprises the following steps: mixing raw materials containing a molecular sieve, a copper source, a second metal source, an ester compound and an alcohol compound, and then impregnating the raw materials with an alkali solution to obtain the copper-based bimetallic catalyst; and the second metal source is selected from one of zinc nitrate, gallium nitrate, iron nitrate and indium nitrate. The application is matched with a continuous reactor-fixed bed, and the production efficiency of 2-methylpropenol is greatly improved. Under the condition that hydrogen is used as a reducing agent and without a solvent, the conversion rate of methacrolein on the bimetallic catalyst reaches 85%, the selectivity of 2-methylpropenol is 90%, and meanwhile, the catalyst can be stably operated for a long time.

Description

Technical Field

[0001] This application relates to a method for preparing a copper-based bimetallic catalyst, the copper-based catalyst and its application, belonging to the field of chemical technology. Background Technology

[0002] With the advancement of national infrastructure construction, the demand for polycarboxylate-based cement water-reducing agents has been increasing year by year. 2-Methylpropenol is an important raw material for the preparation of polycarboxylate-based cement water-reducing agents. In addition, 2-methylpropenol can also be used in the production of surfactants and synthetic resin additives.

[0003] Based on the preparation routes of 2-methylpropenol, its production processes are artificially divided into four types: 1. Chlor-alkali method, 2. Hydrogen transfer method, 3. Selective hydrogenation method, and 4. Dehydration method. Among these, the chlor-alkali method is currently the main method used in industry. To overcome the process inconvenience caused by the use of chlorine in the chlor-alkali method, and considering the full utilization of the large amount of C4 isobutylene byproducts from petroleum and coal chemical processes, we developed an oxide-modified molecular sieve-supported metal catalyst for the preparation of 2-methylpropenol. Summary of the Invention

[0004] To address the shortcomings of current industrial applications, this invention utilizes an innovative catalyst structural design to induce selective hydrogenation reactions. Post-treatment methods are employed to universally enhance the mass transfer capacity of the molecular sieve. Coupled with a continuous reactor, the production capacity is effectively increased, and continuous production of 2-methylpropenol is achieved using hydrogen as a reducing agent under solvent-free conditions.

[0005] This application focuses on catalysts and optimizes the design and preparation methods of catalysts to achieve a better method.

[0006] Molecular sieves have advantages such as low cost, easy availability, stable structure, and large specific surface area, and are widely used in petrochemical, gas separation and other fields. Modification of molecular sieves can yield catalyst supports with even better performance.

[0007] The Cu-based bimetallic catalyst supported on molecular sieves involved in this application has good activity, high selectivity and strong stability, and has great potential industrial application value.

[0008] According to one aspect of this application, a method for preparing a copper-based bimetallic catalyst is provided, the method comprising:

[0009] The copper-based bimetallic catalyst is obtained by mixing raw materials containing molecular sieves, copper source, second metal source, ester compound, and alcohol compound, and then impregnating them with an alkaline solution.

[0010] The second metal source is selected from one of zinc nitrate, gallium nitrate, iron nitrate, indium nitrate, and cobalt nitrate.

[0011] Optionally, the alcohol compound is selected from at least one of ethanol, methanol, isopropanol, and butanol.

[0012] Optionally, the ester compound is selected from at least one of tetrabutyl titanate and titanium tetrachloride.

[0013] Optionally, the molar ratio of the molecular sieve: copper source: second metal source: ester compound: alcohol compound is 1:10~1:10~1:10~1:10~1.

[0014] The amount of the molecular sieve is measured in its own molar quantity, the amount of the copper source is measured in the molar quantity of copper element, the amount of the second metal source is measured in the molar quantity of the second metal element, the amount of the ester compound is measured in its own molar quantity, and the amount of the alcohol compound is measured in its own molar quantity.

[0015] Optionally, the alkaline solution is selected from at least one of ammonia, sodium carbonate, sodium bicarbonate, and sodium hydroxide.

[0016] Optionally, the mass ratio of the alkaline solution to the molecular sieve is 5:1 to 20:1.

[0017] Optionally, the concentration of the alkaline solution is 0.1 to 0.9 M.

[0018] Optionally, the copper source is selected from at least one of copper nitrate and copper sulfate.

[0019] Optionally, the molecular sieve is selected from at least one of ZSM-22 molecular sieve, Hβ type molecular sieve, and ZSM-5 molecular sieve.

[0020] Optionally, the silicon-to-aluminum atomic ratio of the molecular sieve is 10 to 300.

[0021] Optionally, the raw material further includes a carrier selected from one of zirconium oxynitrate, ammonium tungstate, and ammonium molybdate.

[0022] Optionally, the metal oxide is at least one of TiO2, Nb2O5, ZrO2, and WO3.

[0023] Optionally, the mass ratio of the carrier to the molecular sieve is 10:1 to 1:10.

[0024] Optionally, the alkaline solution further includes an auxiliary agent selected from triblock polymer F127 and / or hexadecyltrimethylammonium bromide.

[0025] Optionally, the mass ratio of the auxiliary agent to the alkaline solution is 100:1 to 10:1.

[0026] Optionally, the impregnation process further includes drying and roasting; the drying time is 24–48 hours, and the drying temperature is 25–150°C.

[0027] Optionally, the drying time is selected from any value among 24h, 36h, 40h, and 48h, or a range between any two of the above.

[0028] Optionally, the drying temperature is selected from any value of 25°C, 50°C, 75°C, 100°C, 125°C, or 150°C, or a range between any two of the above.

[0029] Optionally, the calcination time is 1 to 5 hours, and the calcination temperature is 150 to 950°C.

[0030] Optionally, the roasting time is selected from any value of 1h, 2h, 3h, 4h, 5h or a range between any two of the above points.

[0031] Optionally, the roasting temperature is selected from any value of 150℃, 200℃, 300℃, 400℃, 500℃, 800℃, 900℃, 950℃ or a range between any two of the above points.

[0032] Optionally, the roasting atmosphere is selected from at least one of air atmosphere, carbon dioxide atmosphere, and nitrogen atmosphere.

[0033] According to another aspect of this application, a copper-based bimetallic catalyst prepared by the above-described preparation method is provided, wherein the loading of metallic copper is 5 to 25 wt.% of the mass of the copper-based bimetallic catalyst.

[0034] Optionally, in the copper-based bimetallic catalyst, the atomic ratio of metallic copper to the second metal is 20:1 to 1:2.

[0035] Optionally, the second metal is selected from zinc, gallium, iron, indium, tin, and cobalt.

[0036] According to another aspect of this application, a copper-based bimetallic catalyst prepared by the above-described preparation method is provided, and the application of the above-described copper-based bimetallic catalyst in the selective hydrogenation of methacrolein to 2-methylpropenol is provided.

[0037] Optionally, the copper-based bimetallic catalyst is pre-reduced under a reducing atmosphere and then reacted with methacrolein and hydrogen to produce 2-methylpropenol.

[0038] Optionally, the pre-reduction time is 2h to 3h, and the pre-reduction temperature is 300 to 800℃.

[0039] Optionally, the pre-reduction temperature is selected from any value of 300℃, 400℃, 500℃, 600℃, 700℃, 800℃ or a range between any two of the above points.

[0040] Optionally, the pre-restore time is selected from any value among 2h, 2.5h, and 3h, or a range between any two of the above points.

[0041] Optionally, the reducing atmosphere is selected from a carbon monoxide atmosphere and / or a hydrogen atmosphere.

[0042] Optionally, the molar ratio of hydrogen to methacrolein is 1:1 to 20:1.

[0043] Optionally, the molar ratio of hydrogen to methacrolein is selected from any value among 1:1, 5:1, 10:1, 15:1, 20:1, or a range between any two of the above.

[0044] Optionally, the reaction pressure is 0.1 to 5.0 MPa, and the reaction temperature is 50 to 250 °C.

[0045] Optionally, the mass hourly space velocity (HHSV) of the methacrolein is 0.5–5 h⁻¹. -1 .

[0046] Optionally, the mass hourly space velocity (MSV) of the methacrolein is selected from 0.5 h⁻¹. -1 1h -1 2h -1 3h -1 4h -1 5h -1 Any value in the range or any two points mentioned above.

[0047] As a specific implementation method, the present invention is achieved through the following technical solution:

[0048] The first solution adopted in this invention:

[0049] (1) Prepare an aqueous solution with a concentration of 0.1 to 0.9 M using one or more of sodium hydroxide, sodium carbonate, sodium bicarbonate, and ammonia.

[0050] (2) Add one of the ZSM-5 molecular sieves with a silicon-to-aluminum ratio of 10 to 300 to the above solution, with the mass ratio of the solution to the molecular sieve being between 5 and 20.

[0051] (3) Stir the above solution vigorously and keep the temperature between 30 and 90°C for 10 to 120 minutes.

[0052] (4) Centrifuge and wash the treated sample 7 times and filter it.

[0053] (5) Dry the filtered sample at 25-150℃ for 24 hours.

[0054] (6) The sample is roasted in one or more of nitrogen, argon and air at a temperature between 150 and 950°C for a time between 1 and 5 hours.

[0055] (7) Prepare a solution by mixing copper nitrate with one of zinc nitrate, gallium nitrate, iron nitrate, or indium nitrate. Simultaneously, add one of zirconium oxynitrate or ammonium tungstate to the solution. Impregnate the prepared molecular sieve support with the aqueous solution. The loading of metallic Cu is between 5 and 25 wt.%, and the atomic ratio of metallic Cu to the second metal in the catalyst is between 20:1 and 1:2. The mass of the oxide accounts for 5 to 20 wt.% of the total mass of the catalyst.

[0056] (8) The sample was dried at 25-150℃ for 24 hours.

[0057] (9) The sample is roasted in one or more of nitrogen, argon and air at a temperature between 150 and 950°C for a time between 1 and 5 hours.

[0058] (10) The calcined catalyst is pressed into tablets and crushed into 20-40 mesh particles, and then loaded into a fixed bed reactor to reduce the catalyst in situ using hydrogen in the range of 300-750°C.

[0059] (11) The reaction temperature is between 50 and 250°C, and the space velocity is between 0.5 and 5 h⁻¹. -1 The ratio of hydrogen to methacrolein is between 1 and 20.

[0060] The second solution adopted in this invention:

[0061] (1) Prepare an aqueous solution with a concentration of 0.1 to 0.9 M using one or more of sodium hydroxide, sodium carbonate, sodium bicarbonate and ammonia, and add 0.5 g of CTAB and / or triblock copolymer F127 to it.

[0062] (2) Add one type of Hβ molecular sieve with a silicon-to-aluminum ratio of 1 to 15 to the above solution, with the mass ratio of solution to molecular sieve between 5 and 20.

[0063] (3) Stir the above solution vigorously and keep the temperature between 30 and 90°C for 10 to 120 minutes.

[0064] (4) Centrifuge and wash the treated sample 7 times and filter it.

[0065] (5) Dry the filtered sample at 25-150℃ for 24 hours.

[0066] (6) The sample is roasted in one or more of nitrogen, argon and air at a temperature between 150 and 950°C for a time between 1 and 5 hours.

[0067] (7) Prepare a solution by mixing copper nitrate with one of zinc nitrate, gallium nitrate, iron nitrate, or indium nitrate. Simultaneously, add one of zirconium oxynitrate or ammonium tungstate to the solution. Impregnate the prepared molecular sieve support with the aqueous solution. The loading of metallic Cu is between 5 and 25 wt.%, and the atomic ratio of metallic Cu to the second metal in the catalyst is between 20:1 and 1:2. The mass of the oxide accounts for 5 to 20 wt.% of the total mass of the catalyst.

[0068] (8) The sample was dried at 25-150℃ for 24 hours.

[0069] (9) The sample is roasted in one or more of nitrogen, argon and air at a temperature between 150 and 950°C for a time between 1 and 5 hours.

[0070] (10) The calcined catalyst is pressed into tablets and crushed into 20-40 mesh particles, and then loaded into a fixed bed reactor to reduce the catalyst in situ using hydrogen in the range of 300-750°C.

[0071] (11) The reaction temperature is between 50 and 250°C, and the space velocity is between 0.5 and 5 h⁻¹. -1 The ratio of hydrogen to methacrolein is between 1 and 20.

[0072] The third solution adopted in this invention:

[0073] (1) Prepare an aqueous solution with a concentration of 0.1 to 0.9 M using one or more of sodium hydroxide, sodium carbonate, sodium bicarbonate and ammonia, and add 0.5 g of CTAB and / or triblock copolymer F127 to it.

[0074] (2) Thoroughly mix one of the ZSM-5 molecular sieves with a silicon-to-aluminum ratio of 10–300, copper nitrate, zinc nitrate (or one of gallium nitrate, iron nitrate, or indium nitrate), tetrabutyl titanate, and ethanol. The loading of metallic Cu is between 5 and 25 wt.%, and the atomic ratio of metallic Cu to the second metal in the catalyst is between 20:1 and 1:2. The mass of the oxide accounts for 5 to 20 wt.% of the total mass of the catalyst.

[0075] (3) Stir the above solution vigorously and keep the temperature between 30 and 90°C, and slowly add the alkaline solution from (1) dropwise. After the addition is complete, keep it between 10 and 120 minutes.

[0076] (4) Centrifuge and wash the treated sample 7 times and filter it.

[0077] (5) Dry the filtered sample at 25-150℃ for 24 hours.

[0078] (6) The sample is roasted in one or more of nitrogen, argon and air at a temperature between 150 and 950°C for a time between 1 and 5 hours.

[0079] (7) The calcined catalyst is pressed into tablets and crushed into 20-40 mesh particles, and then loaded into a fixed bed reactor to reduce the catalyst in situ using hydrogen in the range of 300-750°C.

[0080] (8) The reaction temperature is between 50 and 250°C, and the space velocity is between 0.5 and 5 h⁻¹. -1 The ratio of hydrogen to methacrolein is between 1 and 20.

[0081] The beneficial effects that this application can produce include:

[0082] Compared to noble metal catalysts such as Pt, Pd, and Ir, this invention provides a copper-based bimetallic catalyst supported on molecular sieves that is relatively inexpensive to prepare, exhibits high reactivity and selectivity for the target product, and possesses extremely strong stability. Production is carried out in a continuous reactor under solvent-free and relatively mild reaction conditions. The heterogeneous catalyst facilitates separation from the product, and post-treatment of the molecular sieve effectively improves the mass transfer capacity of the catalytic system, making the reaction easier to proceed. Under solvent-free conditions with hydrogen as the reducing agent, the conversion rate of methacrolein on the bimetallic catalyst reaches 85%, and the selectivity for 2-methylpropenol is 90%, while the catalyst can operate stably for a relatively long period. Attached Figure Description

[0083] Figure 1 This is the H2-TPR characterization diagram of the copper-based catalyst in Example 1 of this application.

[0084] Figure 2 This is the H2-TPR characterization diagram of the copper-based catalyst in Example 2 of this application. Detailed Implementation

[0085] The present application is described in detail below with reference to the embodiments, but the present application is not limited to these embodiments.

[0086] Unless otherwise specified, all raw materials used in the embodiments of this application were purchased through commercial channels.

[0087] Conversion rate = 1 - Amount of unconverted reactants / Total amount of reactants.

[0088] Selectivity = Amount of product / Amount of reactants converted.

[0089] This application uses a MacCard chemisorption analyzer to characterize the catalyst.

[0090] Example 1

[0091] Mix 10g NaOH with 100ml water to prepare a solution and store it in a PTFE bottle. Place the solution in a water bath at a constant temperature of 80℃. Weigh 10g of ZSM-5 molecular sieve (silicon-to-aluminum ratio 25), add it to the solution, maintain for 40 minutes, then centrifuge and wash the sample 7 times. Place the filtered sample in a 100℃ oven and dry for 24 hours. Then calcine the dried sample at 600℃ for 5 hours under a nitrogen atmosphere. Dissolve 1g copper nitrate, 0.5g gallium nitrate, and 0.2g ammonium molybdate in 4ml deionized water. Weigh 3g of the treated molecular sieve sample and impregnate the molecular sieve with the metal salt solution. Let it stand at 25℃ for 24 hours, then dry at 120℃ for 24 hours, and finally calcine at 500℃ for 5 hours. Compress the calcined catalyst into tablets, crush them to 20-40 mesh particles, and load them into a fixed-bed reactor for in-situ reduction using hydrogen at 750℃. After the fixed-bed reactor is cooled to 180°C, methacrolein is introduced at a space velocity of 2 h⁻¹. -1 The ratio of hydrogen to methacrolein was 10, and the selectivity of methacrolein alcohol and isobutyraldehyde is shown in Table 1; the H2-TPR characterization results of the calcined catalyst are as follows: Figure 1 As shown, from Figure 1 It can be seen that metallic Cu forms a strong interaction with other components of the catalyst.

[0092] Example 2

[0093] Mix 10g NaOH, 0.5g cetyltrimethylammonium bromide (CTAB), and 100ml water to prepare a solution, and store it in a polytetrafluoroethylene bottle. Place the solution in a water bath at a constant temperature of 80℃. Weigh 10g of Hβ molecular sieve (silicon-to-aluminum ratio 10), add it to the solution, maintain for 40min, then centrifuge and wash the sample 7 times. Place the filtered sample in a 100℃ oven and dry for 24h. Then, calcine the dried sample at 600℃ for 5h under a nitrogen atmosphere. Dissolve 1g copper nitrate, 0.5g gallium nitrate, and 0.3g zirconium oxynitrate in 4ml deionized water. Weigh 3g of the treated molecular sieve sample and immerse the sieve in the metal salt solution. Let it stand at 25℃ for 24h, then dry at 120℃ for 24h, and finally calcine at 500℃ for 5h. The calcined catalyst was compressed into tablets and crushed to 20-40 mesh particles, then loaded into a fixed-bed reactor for in-situ reduction with hydrogen at 750°C. After the fixed-bed reactor cooled to 180°C, methacrolein was introduced at a space velocity of 2 h⁻¹. -1The ratio of hydrogen to methacrolein is 10. The selectivity of methacrolein alcohol and isobutyraldehyde is shown in Table 1. Figure 2 It can be seen that the interaction between the metal active sites or with the support is weak, and the dispersion is slightly inferior.

[0094] Example 3

[0095] Dissolve 4g sodium carbonate, 6g sodium hydroxide, and 0.5g F127 in 100ml of water to prepare solution A. Add 10g ZSM-5 molecular sieve (silicon-to-aluminum ratio 30), 1g copper nitrate, 0.2g ferric nitrate, and 5g tetrabutyl titanate to a polytetrafluoroethylene bottle containing 100ml of ethanol and maintain a constant temperature of 60℃. Slowly add solution A to the molecular sieve suspension using a constant flow pump and maintain the temperature for 60min. Centrifuge and wash the treated sample seven times and filter. Dry the filtered sample at 120℃ for 24h. Finally, calcine at 500℃ for 5h. Press the calcined catalyst into tablets, crush them to 20-40 mesh, and load them into a fixed-bed reactor. Reduce the catalyst in situ using hydrogen at 750℃. After the fixed-bed reactor cools to 180℃, purge with methacrolein at a space velocity of 2h. -1 The ratio of hydrogen to methacrolein is 10, and the selectivity of methacrolein and isobutyraldehyde is shown in Table 1.

[0096] Comparative Example

[0097] Dissolve 1g of copper nitrate in 4ml of deionized water. Weigh 3g of untreated ZSM-5 molecular sieve (silicon-to-aluminum atomic ratio 30) sample and impregnate the molecular sieve with silver nitrate and ammonium molybdate solution. Let stand at 25℃ for 24h, then dry at 120℃ for 24h, and finally calcine at 500℃ for 5h. Compress and crush the calcined catalyst into 20-40 mesh particles, and load them into a fixed-bed reactor for in-situ reduction of the catalyst using hydrogen at 750℃. After the fixed-bed reactor cools to 180℃, introduce methacrolein at a space velocity of 2h. -1 The ratio of hydrogen to methacrolein is 10, and the selectivity of methacrolein and isobutyraldehyde is shown in Table 1.

[0098] Table 1 Activity evaluation results in the examples

[0099]

[0100]

[0101] As can be seen from Table 1, Example 3 exhibits good activity and selectivity for the target product in the specific preparation method described above.

[0102] The above description is merely a few embodiments of this application and is not intended to limit this application in any way. Although this application discloses preferred embodiments as described above, it is not intended to limit this application. Any changes or modifications made by those skilled in the art without departing from the scope of the technical solution of this application using the disclosed technical content are equivalent to equivalent implementation cases and fall within the scope of the technical solution.

Claims

1. A method for preparing a copper-based bimetallic catalyst for the selective hydrogenation of methacrolein to 2-methylpropenol, characterized in that, The preparation method includes: The copper-based bimetallic catalyst is obtained by mixing raw materials containing molecular sieves, copper source, second metal source, ester compound, and alcohol compound, and then impregnating them with an alkaline solution. The second metal source is selected from one of zinc nitrate, gallium nitrate, iron nitrate, indium nitrate, and cobalt nitrate; the alcohol compound is selected from at least one of ethanol, methanol, isopropanol, and butanol. The ester compound is selected from at least one of tetrabutyl titanate and titanium tetrachloride; The molar ratio of the molecular sieve, copper source, second metal source, ester compound, and alcohol compound is 1:10~1:10~1:10~1:10~1; The amount of the molecular sieve is measured in its own molar amount, the amount of the copper source is measured in the molar amount of copper element, the amount of the second metal source is measured in the molar amount of the second metal element, the amount of the ester compound is measured in its own molar amount, and the amount of the alcohol compound is measured in its own molar amount. The alkaline solution also includes an auxiliary agent selected from triblock polymer F127 and / or hexadecyltrimethylammonium bromide.

2. The preparation method according to claim 1, characterized in that, The alkaline solution is selected from at least one of ammonia, sodium carbonate, sodium bicarbonate, and sodium hydroxide. The mass ratio of the alkaline solution to the molecular sieve is 5:1 to 20:

1. The concentration of the alkaline solution is 0.1~0.9M.

3. The preparation method according to claim 1, characterized in that, The copper source is selected from at least one of copper nitrate and copper sulfate; The molecular sieve is selected from at least one of ZSM-22 molecular sieve, Hβ type molecular sieve, and ZSM-5 molecular sieve; The molecular sieve has a silicon-to-aluminum atomic ratio of 10 to 300.

4. The preparation method according to claim 1, characterized in that, The raw materials also include a carrier, which is selected from one of zirconium oxynitrate, ammonium tungstate, and ammonium molybdate. The mass ratio of the carrier to the molecular sieve is 10:1 to 1:10; The mass ratio of the auxiliary agent to the alkaline solution is 100:1 to 10:

1.

5. The preparation method according to claim 1, characterized in that, The impregnation process further includes drying and calcination; the drying time is 24~48 h, and the drying temperature is 25~150 ℃; The roasting time is 1-5 h, and the roasting temperature is 150-950 ℃; The roasting atmosphere is selected from at least one of air atmosphere, carbon dioxide atmosphere, and nitrogen atmosphere.

6. The copper-based bimetallic catalyst prepared by the preparation method according to any one of claims 1 to 5, characterized in that, The loading of metallic copper is 5-25 wt.% of the mass of the copper-based bimetallic catalyst. In the copper-based bimetallic catalyst, the atomic ratio of metallic copper to the second metal is 10:1 to 1:2; The second metal is selected from one of zinc, gallium, iron, indium, and cobalt.

7. The application of the copper-based bimetallic catalyst prepared by the preparation method according to any one of claims 1 to 5, and the copper-based bimetallic catalyst according to claim 6, in the selective hydrogenation of methacrolein to 2-methylpropenol.

8. The application according to claim 7, characterized in that, After the copper-based bimetallic catalyst is pre-reduced under a reducing atmosphere, it is then contacted with methacrolein and hydrogen to react and generate 2-methylpropenol. The pre-reduction time is 2 h to 3 h, and the pre-reduction temperature is 300 to 800 ℃; The reducing atmosphere is selected from carbon monoxide atmosphere and / or hydrogen atmosphere.

9. The application according to claim 8, characterized in that, The molar ratio of hydrogen to methacrolein is 1:1 to 20:1; The reaction pressure is 0.1~5.0 MPa, and the reaction temperature is 50~250 ℃; The mass hourly space velocity (MSV) of the methacrolein is 0.5–5 h⁻¹. -1 .

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