High-selectivity catalyst for gaseous aldehyde hydrogenation to alcohol and preparation method thereof

Abstract

The application discloses a high-selectivity catalyst for gas-phase aldehyde hydrogenation to alcohol and a preparation method thereof. The method comprises the following steps: firstly, an aluminum source, a magnesium source, a template agent and water are mixed to prepare a first salt solution, and then the first salt solution and a precipitating agent are subjected to parallel flow precipitation to form a first precipitate; secondly, copper nitrate, zinc nitate and water are mixed to prepare a second salt solution, and then the second salt solution and the precipitating agent are dropped into the precipitate prepared in the first step by means of differential parallel flow co-precipitation; and thirdly, the mixture obtained after co-precipitation in the first step and the second step is uniformly mixed, and then is subjected to aging under stirring, so that the first precipitate is completely neutralized, and then a heat-conducting additive is added. The catalyst prepared by the method has high specific surface area and high pore volume, the mass transfer and heat transfer efficiency is improved, the side reaction is reduced, meanwhile, the zinc oxide coating part of the copper oxide weakens the generation of C16 ester, and the selectivity and conversion rate of the gas-phase aldehyde hydrogenation reaction are further improved.

Description

Technical Field

[0001] This invention belongs to the field of catalyst preparation technology, specifically a highly selective gas-phase aldehyde hydrogenation catalyst for alcohol production and its preparation method. Background Technology

[0002] Alcohols can be used as organic solvents and organic chemical raw materials, and are widely used in fine chemical fields such as lipids, plasticizers, and surfactants. With the widespread application of butanol and octanol processes, the demand for aldehyde hydrogenation catalysts has increased, leading to the development of a series of Cu-Cr based hydrogenation catalysts. Due to increasingly stringent environmental requirements, Cu-Zn catalysts gradually replaced Cu-Cr catalysts in the 1990s.

[0003] The aldehyde hydrogenation catalysts used domestically are mainly the OXO-1 and OXO-2 gas-phase aldehyde hydrogenation catalysts from Southern German Chemicals. With the development of VAH-1 / VAH-2 by the China Petroleum & Chemical Research Institute, the monopoly of foreign gas-phase aldehyde hydrogenation catalysts has been gradually broken. Meanwhile, the Nanjing Research Institute of Petrochemical Technology of China Petroleum & Chemical Corporation has also developed the NCH6-1 / NCH6-2 gas-phase aldehyde hydrogenation catalyst. The preparation methods and compositions of these catalysts are similar, all being CuZn-based catalysts prepared by co-precipitation. However, these catalysts still suffer from poor metal sintering stability, low heat transfer efficiency, and high rates of side reactions. In particular, the heavy components (C10-C16 and above, boiling points above 190℃) generated at high temperatures have complex compositions, mostly consisting of aldehyde condensates (including acetals, cyclic acetals, etc.) and long-chain esters. Currently, controlling the formation of heavy components, especially C16 esters, is key to improving octanol purity and reducing energy consumption.

[0004] Methods to improve aldehyde hydrogenation catalysts mainly focus on optimizing preparation methods and conditions, adding additives, modifying the mass and heat transfer properties of the support, and improving the stability or selectivity of the catalyst.

[0005] Union Carbide Corporation of the United States reported in its patent CN1050994A that small amounts of alkali metals (such as sodium, potassium, lithium, cesium), nickel, cobalt, and mixtures thereof as selective modifiers can improve the selectivity of aldehyde hydrogenation to alcohol production catalysts; the preparation process involves first preparing the catalyst precursor and then modifying it. Tianjin Chemical Research Institute, in its Chinese patent CN1695802A, directly introduced metal salts (one or more of Mg, Ca, Mn, and Al) as promoters during catalyst synthesis to adjust the surface acidity of the catalyst, which can improve the selectivity of alcohols to a certain extent.

[0006] The Nanjing Chemical Research Institute of China National Petroleum Corporation (CNPC) employs a precipitation reaction using copper, zinc, and aluminum nitrates along with a precipitant in Chinese patents CN1381311A and CN1381312A. The catalyst exhibits good selectivity, but the strong bond between Cu and Al results in poor reactivity for aldehyde hydrogenation. Chinese patent CN100398202C uses a distributed continuous co-precipitation method to prepare the catalyst. First, a zinc-aluminum salt solution and a precipitant are neutralized in a co-current flow. After aging, the copper-zinc salt solution and the precipitant are neutralized in a co-current flow without removing the mother liquor, followed by aging, and finally drying and calcination. Zn 2+ And Al 3+ The combination in the form of ZnAl2O4 reduces the acidity of the catalyst surface, thereby reducing etherification and esterification reactions. Patent CN114471578A further utilizes sodium aluminate as the aluminum source for synthesis, more effectively suppressing side reactions.

[0007] Wanhua Chemical, in its Chinese patent CN 108043411A, employs a simultaneous precipitation method to precipitate copper and zinc at two different temperatures, resulting in two different pore structures and forming a biporous system. This catalyst exhibits high dispersion of active components and good mass / heat transfer performance. It demonstrates excellent activity and selectivity, reducing the formation of byproducts n-butyl butyrate and octanol, and improving the selectivity of n-butanol.

[0008] The hydrogenation of octenal to octanol involves low catalyst heat transfer efficiency and high levels of side reactions. In particular, the high-temperature formation of C10-C16 and higher heavy components (boiling points above 190℃) is complex in composition, mostly consisting of aldehyde condensation polymers (including acetals, cyclic acetals, etc.) and long-chain esters. Therefore, improving the catalyst to enhance its mass and heat transfer efficiency is crucial for preparing highly selective and highly active aldehyde hydrogenation catalysts. Summary of the Invention

[0009] The purpose of this invention is to overcome at least one defect (deficiency) of the prior art and provide a method for preparing a highly selective gas-phase aldehyde hydrogenation catalyst for alcohol production, as well as the catalyst itself. In the preparation method, aluminum salt is preferentially precipitated first, then the pH is slowly adjusted to control the preferential precipitation of copper, followed by zinc precipitation and partial copper coating. After aging, a thermally conductive additive is added to form a catalyst with high specific surface area and high pore volume, improving mass and heat transfer efficiency and effectively reducing the formation of byproducts such as C16 esters.

[0010] To achieve the above-mentioned objectives, the specific technical solution of the present invention is as follows:

[0011] A method for preparing a highly selective gas-phase aldehyde hydrogenation catalyst for alcohol production includes the following steps:

[0012] The first step is to mix the aluminum source, magnesium source, template agent and water to prepare the first salt solution, and then mix it with the precipitant to form the first precipitate.

[0013] The second step involves preparing a second salt solution by mixing copper nitrate, zinc nitrate, and water, and then adding the mixed solution and precipitant dropwise in a differential and parallel flow into the precipitate formed in the first step.

[0014] The third step is to uniformly mix the co-precipitated mixture obtained in steps one and two, and then keep it under heat and age it while stirring to ensure that the precipitate is completely neutralized.

[0015] The fourth step involves adding or not adding a heat-conducting agent to the aged precipitate, stirring until evenly mixed; then washing with water and filtering to obtain a filter cake, and drying the filter cake to obtain powder, which is then calcined at high temperature.

[0016] The fifth step involves adding graphite and water to the calcined material for granulation, followed by tableting to obtain a catalyst, which is then used for the gas-phase hydrogenation of aldehydes to produce alcohols.

[0017] In a preferred embodiment of this application, the aluminum source is any one or a mixture of aluminum nitrate, sodium aluminate, and aluminum isopropoxide; the concentration of aluminum in the aluminum source is 0.1–1 mol / L; the magnesium source is any one or a mixture of magnesium nitrate, magnesium carbonate, and basic magnesium carbonate; the concentration of magnesium in the magnesium source is 0.1–1 mol / L; the template agent is any one of sorbitol, hexamethylenediamine, polyvinylpyrrolidone, or ethylenediaminetetraacetic acid; the concentration of the template agent is 0.01 ml / L–0.1 mol / L.

[0018] In a preferred embodiment of this application, in the preparation method of the highly selective gas-phase aldehyde hydrogenation to alcohol catalyst, the concentration of zinc ions in the second salt solution is 0.5–2 mol / L; the concentration of copper ions is 0.2–1 mol / L; and the concentration of aluminum ions is 0–1 mol / L.

[0019] In a preferred embodiment of this application, in the preparation method of the highly selective gas-phase aldehyde hydrogenation to alcohol catalyst, the precipitant used in the first and second steps is an alkaline precipitant; the alkaline precipitant is selected from any one or a mixture of sodium carbonate, sodium bicarbonate and sodium hydroxide, and its concentration is 0.8-4 mol / L. Sodium bicarbonate is more preferred for the first precipitation step, and sodium carbonate is more preferred for the second precipitation step.

[0020] As a preferred embodiment of this application, in the preparation method of the highly selective gas-phase aldehyde hydrogenation to alcohol catalyst, the differential co-flow co-precipitation method used in the second step has a flow rate of 15-30 mL / min for the metal mixed solution and a flow rate of 5-20 mL / min for the precipitant solution. After the metal mixed solution is completely added, the flow rate of the precipitant solution is adjusted to 30 mL / min.

[0021] As a preferred embodiment of this application, in the preparation method of the highly selective gas-phase aldehyde hydrogenation to alcohol catalyst, the conditions for the first step co-precipitation and the second step differential co-precipitation are as follows: co-precipitation temperature is room temperature to 75°C, rotation speed is 200-500 rpm / min, co-precipitation time is 20 to 70 minutes, and the final pH value of co-precipitation is 7.0 to 7.5.

[0022] In a preferred embodiment of this application, in the preparation method of the highly selective gas-phase aldehyde hydrogenation to alcohol catalyst, the aging temperature in the third step is 60°C to 80°C, and the aging time is 1h to 2h.

[0023] In a preferred embodiment of this application, in the preparation method of the highly selective gas-phase aldehyde hydrogenation to alcohol catalyst, the thermally conductive aid added in the fourth step is any one or a mixture of several of MgAl alloy powder, SiCuAl alloy powder, Si3N4, BN and SiC.

[0024] As a preferred embodiment of this application, in the preparation method of the highly selective gas-phase aldehyde hydrogenation to alcohol catalyst, the high-temperature calcination temperature in the fourth step is 340-400°C, and the calcination time is 4-6 hours.

[0025] The highly selective gas-phase aldehyde hydrogenation catalyst for alcohol production prepared by any of the methods described above contains, by mass percentage, 30%–40% copper oxide, 55%–69% zinc oxide, 1%–20% aluminum oxide, 1%–20% magnesium oxide, 0%–2% thermally conductive agent, and 1%–3% graphite, with a total mass percentage of 100%.

[0026] Furthermore, the BET specific surface area of ​​the highly selective gas-phase aldehyde hydrogenation to alcohol catalyst is 40–100 m². 2 / g, pore volume 0.15~0.4cm 2 / g, with an average pore radius of 10–20 nm.

[0027] Compared with existing technologies, the beneficial effects of this invention are:

[0028] (i) In this invention, aluminum source, magnesium source and precipitant are first precipitated to form a first precipitate. Then, the acid-base drop acceleration rate is controlled to preferentially precipitate copper oxide. Subsequently, zinc oxide is precipitated and partially encapsulates copper oxide to form a catalyst with high specific area and high pore volume, which improves mass and heat transfer efficiency and reduces side reactions.

[0029] (ii) The addition of thermally conductive agents reduces the hot spot temperature of the reaction, effectively reducing the formation of byproducts such as C16 esters under high temperature conditions, and further improving the octanol selectivity and conversion rate of the gas-phase aldehyde hydrogenation reaction. Attached Figure Description

[0030] Figure 1 Comparison diagram of the effects of embodiments 2, 5 and 7 of the present invention with comparative examples 1 and 2. Detailed Implementation

[0031] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. These embodiments are implemented based on the technical solutions of this invention, and detailed implementation methods and processes are provided. However, the scope of protection of this invention is not limited to the following embodiments. Experimental methods in the following embodiments that do not specify specific conditions are generally performed under conventional conditions.

[0032] Example 1:

[0033] A highly selective gas-phase aldehyde hydrogenation catalyst for alcohol production is prepared by the following steps:

[0034] Step 1: Prepare a first salt solution using 6.0g aluminum nitrate, 6.0g magnesium nitrate, 0.1g polyvinylpyrrolidone, and 100ml deionized water. Then, prepare a precipitant solution using 16.0g sodium carbonate and 100mL deionized water. Add the first salt solution and the precipitant solution dropwise in parallel into a reaction vessel equipped with a mechanical stirrer, maintaining the pH at 7.0 during the process. The precipitation temperature is 75℃, and the stirring speed is 200rpm / min.

[0035] Step 2: Prepare a second salt solution using 94.5g zinc nitrate, 50.5g copper nitrate, and 1000mL deionized water; prepare a precipitant solution using 100.0g sodium carbonate and 1200mL deionized water; add the second salt solution and precipitant solution dropwise in parallel to the precipitate formed in Step 1, controlling the flow rate of the metal mixture solution at 35mL / min and the flow rate of the precipitant solution at 15mL / min. After the metal mixture solution has been completely added, adjust the flow rate of the precipitant solution to 30mL / min and drop until the pH reaches approximately 7.5, stirring at 200rpm / min throughout the process to maintain the precipitation temperature at 75℃.

[0036] Step 3: Stir the co-precipitated mixture obtained in Step 1 and Step 2 at 75°C for 1 hour to ensure complete neutralization of the precipitate;

[0037] Step 4: Wash the aged material from Step 3 several times with deionized water, filter it, dry the filter cake obtained by filtration, and calcine the filter cake at 380℃ for 4 hours.

[0038] Step 5: Add 1.5g of graphite and 10mL of water to the calcined material, granulate, press into tablets, crush, and sieve through a 4-6 mesh screen to obtain the gaseous aldehyde hydrogenation catalyst.

[0039] Example 2

[0040] This embodiment provides a highly selective gas-phase aldehyde hydrogenation catalyst for alcohol production, the preparation method of which includes the following steps:

[0041] Step 1: Prepare a metal solution using 12.0g sodium aluminate, 14.0g magnesium nitrate, 0.3g polyvinylpyrrolidone, and 200ml deionized water. Then, prepare a precipitant solution using 40.0g sodium bicarbonate and 200mL deionized water. Pour the mixed metal solution and precipitant solution dropwise into a mechanically stirred reactor, maintaining the pH at 7.0. The precipitation temperature is 65℃, and the stirring speed is 300rpm / min.

[0042] Step 2: Prepare a mixed metal solution using 189.0g zinc nitrate, 94.2g copper nitrate, and 1000mL deionized water; prepare a precipitant solution using 200.0g sodium carbonate and 1200mL deionized water; add the mixed metal solution and precipitant solution dropwise in parallel to the precipitate formed in Step 1, controlling the flow rate of the mixed metal solution at 35mL / min and the flow rate of the precipitant solution at 15mL / min. After the mixed metal solution has been completely added, adjust the flow rate of the precipitant solution to 30mL / min and drop until the pH reaches approximately 7.5, stirring at 200rpm / min throughout the process to maintain the precipitation temperature at 75℃.

[0043] Step 3: Stir the co-precipitated mixture obtained in Step 1 and Step 2 at 75°C for 1 hour to ensure complete neutralization of the precipitate;

[0044] Step 4: Wash the neutralized and aged material from Step 3 several times with deionized water, filter it, dry the filter cake obtained by filtration, and calcine the filter cake at 380℃ for 4 hours.

[0045] Step 5: Add 4.0g of graphite and 25mL of water to the calcined material to granulate, press into tablets, crush, and sieve through a 4-6 mesh screen to obtain the gaseous aldehyde hydrogenation catalyst.

[0046] Example 3

[0047] This embodiment provides a highly selective gas-phase aldehyde hydrogenation catalyst for alcohol production, the preparation method of which includes the following steps:

[0048] Step 1: Prepare a metal solution using 25.0g aluminum nitrate, 20.0g magnesium nitrate, 0.5g sorbitol, and 350ml deionized water. Then, prepare a precipitant solution using 80g sodium bicarbonate and 350mL deionized water. The mixed metal solution and precipitant solution are then fed dropwise into a mechanically stirred reactor, maintaining the pH at 7.5. The precipitation temperature is 70℃, and the stirring speed is 300rpm / min.

[0049] Step 2: Prepare a mixed metal solution using 283.5g zinc nitrate, 161.5g copper nitrate, and 1000mL deionized water; prepare a mixed precipitant solution using 285.0g sodium carbonate and 1200mL deionized water; add the resulting mixed metal solution and precipitant solution dropwise in parallel at different speeds to the precipitate formed in Step 1. The flow rate of the mixed metal solution is controlled at 30mL / min, and the flow rate of the precipitant solution is controlled at 10mL / min. After the mixed metal solution has been completely added, adjust the flow rate of the precipitant solution to 30mL / min and drop until the pH reaches approximately 7.2. During this process, stir at 250rpm / min to maintain the precipitation temperature at 80℃.

[0050] Step 3: Stir the co-precipitated mixture obtained in Step 1 and Step 2 at 80°C for 1 hour to ensure complete neutralization of the precipitate;

[0051] Step 4: Wash the neutralized and aged material from Step 3 several times with deionized water at 80°C, then filter it. Dry the filter cake obtained from the filter and calcine it at 400°C for 5 hours.

[0052] Step 5: Add 6.0g of graphite and 22mL of water to the calcined material to granulate, press into tablets, crush, and sieve through a 4-6 mesh screen to obtain the gaseous aldehyde hydrogenation catalyst.

[0053] Example 4

[0054] This embodiment provides a highly selective gas-phase aldehyde hydrogenation catalyst for alcohol production, the preparation method of which includes the following steps:

[0055] Step 1: Prepare a metal solution using 50.0g aluminum isopropoxide, 50.0g magnesium nitrate, 2.0g hexamethylenediamine, and 800ml deionized water. Then, prepare a precipitant solution using 160.0g sodium bicarbonate and 800mL deionized water. Pour the mixed metal solution and precipitant solution dropwise into a mechanically stirred reactor, maintaining the pH at 7.0. The precipitation temperature is 75℃, and the stirring speed is 300rpm / min.

[0056] Step 2: Prepare a mixed metal solution using 283g zinc nitrate, 188.4g copper nitrate, and 1000mL deionized water; prepare a precipitant solution using 285g sodium carbonate and 1200mL deionized water; add the mixed metal solution and precipitant solution dropwise in parallel at different speeds to the precipitate formed in Step 1. The flow rate of the mixed metal solution is controlled at 30mL / min, and the flow rate of the precipitant solution is controlled at 10mL / min. After the mixed metal solution has been completely added, adjust the flow rate of the precipitant solution to 30mL / min and drop until the pH reaches approximately 7.2, stirring at 300rpm / min to maintain the precipitation temperature at 80℃.

[0057] Step 3: Stir the co-precipitated mixture obtained in Step 1 and Step 2 at 80°C for 2 hours to age the material and ensure complete neutralization of the precipitate;

[0058] Step 4: Wash the neutralized and aged material from Step 3 several times with deionized water at 80°C, then filter it. Dry the filter cake obtained from the filter and calcine it at 400°C for 5 hours.

[0059] Step 5: Add 6.0g of graphite and 24mL of water to the calcined material to granulate, press into tablets, crush, and sieve through a 4-6 mesh screen to obtain the gaseous aldehyde hydrogenation catalyst.

[0060] Example 5

[0061] This embodiment provides a highly selective gas-phase aldehyde hydrogenation catalyst for alcohol production, the preparation method of which includes the following steps:

[0062] Step 1: Prepare a metal solution using 6g sodium aluminate, 6g magnesium nitrate, 0.1g polyvinylpyrrolidone, and 100ml deionized water. Then, prepare a precipitant solution using 16g sodium bicarbonate and 100mL deionized water. The mixed metal solution and precipitant solution are then fed dropwise into a mechanically stirred reactor, maintaining the pH at 7.0. The precipitation temperature is 70℃, and the stirring speed is 300rpm / min.

[0063] Step 2: Prepare a mixed metal solution using 189.0g zinc nitrate, 94.2g copper nitrate, and 1000mL deionized water; prepare a mixed precipitant solution using 190.0g sodium carbonate and 1200mL deionized water; add the resulting mixed metal solution and precipitant solution dropwise to the precipitate formed in Step 1, controlling the flow rate of the mixed metal solution at 35mL / min and the flow rate of the precipitant solution at 15mL / min. After the mixed metal solution has been completely added, adjust the flow rate of the precipitant solution to 30mL / min and drop until the pH reaches approximately 7.5. Maintain the precipitation temperature at 75℃ and stir at 200rpm / min.

[0064] Step 3: Stir the co-precipitated mixture obtained in Step 1 and Step 2 at 75°C for 1 hour to ensure complete neutralization of the precipitate;

[0065] Step 4: Add 1.0g of magnesium-aluminum alloy powder to the neutralized and aged material from Step 3, stir at 2rpm / min for half an hour, wash several times with deionized water, filter, dry the filter cake, and calcine the filter cake at 380℃ for 4 hours.

[0066] In the fifth step, after calcination, 4.0 g of graphite and 25 mL of water were added to the sample for granulation, pressing, crushing, and sieving through a 4-6 mesh sieve to obtain the copper-zinc-aluminum gas-phase aldehyde hydrogenation catalyst.

[0067] Example 6

[0068] This embodiment provides a highly selective gas-phase aldehyde hydrogenation catalyst for alcohol production, the preparation method of which includes the following steps:

[0069] Step 1: Prepare a metal solution using 25g aluminum nitrate, 25g magnesium nitrate, 0.3g sorbitol, and 350ml deionized water. Then, prepare a precipitant solution using 80g sodium bicarbonate and 350mL deionized water. The mixed metal solution and precipitant solution are then fed dropwise into a mechanically stirred reactor, maintaining the pH at 7.5. The precipitation temperature is 70℃, and the stirring speed is 300rpm / min.

[0070] Step 2: Prepare a mixed metal solution using 189.0g zinc nitrate, 94.2g copper nitrate, and 1000mL deionized water; prepare a mixed precipitant solution using 190.0g sodium carbonate and 1200mL deionized water; add the resulting mixed metal solution and precipitant solution dropwise to the precipitate formed in Step 1, controlling the flow rate of the mixed metal solution at 35mL / min and the flow rate of the precipitant solution at 15mL / min. After the mixed metal solution has been completely added, adjust the flow rate of the precipitant solution to 30mL / min and drop until the pH reaches approximately 7.5. Maintain the precipitation temperature at 75℃ and stir at 200rpm / min.

[0071] Step 3: Stir the co-precipitated mixture obtained in Step 1 and Step 2 at 75°C for 1 hour to ensure complete neutralization of the precipitate;

[0072] Step 4: Add 2g of SiCuAl alloy powder (commercially available product) to the neutralized and aged material from Step 3. Stir at 200rpm / min for half an hour, wash several times with deionized water, filter, dry the filter cake, and calcine the filter cake at 380℃ for 4 hours.

[0073] Step 5: Add 4.0g of graphite and 25ml of water to the calcined sample to granulate, press into tablets, crush, and sieve through a 4-6 mesh sieve to obtain the copper-zinc-aluminum gas-phase aldehyde hydrogenation catalyst.

[0074] Example 7

[0075] This embodiment provides a highly selective gas-phase aldehyde hydrogenation catalyst for alcohol production, the preparation method of which includes the following steps:

[0076] Step 1: Prepare a metal solution using 25.0g sodium aluminate, 25.0g magnesium nitrate, 0.35g polyvinylpyrrolidone, and 350mL deionized water. Then, prepare a precipitant solution using 80.0g sodium bicarbonate and 350mL deionized water. Pour the mixed metal solution and precipitant solution dropwise into a mechanically stirred reactor, maintaining the pH at 7.5. The precipitation temperature is 70℃, and the stirring speed is 300rpm / min.

[0077] Step 2: Prepare a mixed metal solution using 189.0g zinc nitrate, 94.2g copper nitrate, and 1000mL deionized water; prepare a mixed precipitant solution using 200.0g sodium carbonate and 1200mL deionized water; add the resulting mixed metal solution and precipitant solution dropwise to the precipitate formed in Step 1, controlling the flow rate of the mixed metal solution at 35mL / min and the flow rate of the precipitant solution at 15mL / min. After the mixed metal solution has been completely added, adjust the flow rate of the precipitant solution to 30mL / min and drop until the pH reaches approximately 7.5. Maintain the precipitation temperature at 75℃ and stir at 200rpm / min.

[0078] Step 3: Stir the co-precipitated mixture obtained in Step 1 and Step 2 at 75°C for 1 hour to ensure complete neutralization of the precipitate;

[0079] Step 4: Add 2.5g SiC to the neutralized and aged material from Step 3, stir at 200rpm / min for half an hour, wash several times with deionized water, filter, dry the filter cake, and calcine the filter cake at 380℃ for 4 hours.

[0080] Step 5: Add 4.0g of graphite and 25mL of water to granulate, press, crush, and sieve through a 4-6 mesh screen to obtain the gaseous aldehyde hydrogenation catalyst.

[0081] Example 8

[0082] This embodiment provides a highly selective gas-phase aldehyde hydrogenation catalyst for alcohol production, the preparation method of which includes the following steps:

[0083] Step 1: Prepare a metal solution using 6.0g aluminum isopropoxide, 6.0g magnesium nitrate, 0.1g ethylenediaminetetraacetic acid, and 100mL deionized water. Then, prepare a precipitant solution using 16.0g sodium bicarbonate and 100mL deionized water. The mixed metal solution and precipitant solution are then fed dropwise into a mechanically stirred reactor, maintaining the pH at 7.5. The precipitation temperature is 70℃, and the stirring speed is 300rpm / min.

[0084] Step 2: Prepare a mixed metal solution using 189.0g zinc nitrate, 94.2g copper nitrate, and 1000mL deionized water; prepare a mixed precipitant solution using 200.0g sodium carbonate and 1200mL deionized water; add the resulting mixed metal solution and precipitant solution dropwise to the precipitate formed in Step 1, controlling the flow rate of the mixed metal solution at 35mL / min and the flow rate of the precipitant solution at 15mL / min. After the mixed metal solution has been completely added, adjust the flow rate of the precipitant solution to 30mL / min and drop until the pH reaches approximately 7.5. Maintain the precipitation temperature at 75℃ and stir at 200rpm / min.

[0085] Step 3: Stir the co-precipitated mixture obtained in Step 1 and Step 2 at 75°C for 1 hour to ensure complete neutralization of the precipitate;

[0086] Step 4: Add 3.0g Si3N4 to the neutralized and aged material from Step 3, stir at 200rpm / min for half an hour, wash several times with deionized water, filter, dry the filter cake, and calcine the filter cake at 380℃ for 4 hours.

[0087] Step 5: Add 4.0g of graphite and 25mL of water to granulate, press, crush, and sieve through a 4-6 mesh screen to obtain the copper-zinc-aluminum gas-phase aldehyde hydrogenation catalyst.

[0088] Comparative Example 1

[0089] A gas-phase aldehyde hydrogenation catalyst for alcohol production, the preparation method of which includes the following steps:

[0090] Step 1: Prepare the first salt solution using 10.3g zinc nitrate, 2.5g aluminum nitrate, and 100mL deionized water;

[0091] Step 2: Prepare the second salt solution using 94.2g copper nitrate, 189g zinc nitrate, and 1000mL deionized water;

[0092] Step 3: Prepare a mixed precipitant solution using 200.0g sodium carbonate and 1200mL deionized water; add the first salt solution and precipitant solution prepared in step 1 into a reaction vessel equipped with mechanical stirring in parallel dropwise, controlling the pH at around 7.0, maintaining the precipitation temperature at 75℃, and stirring at a speed of 200rpm / min; after the material titration is complete, maintain the temperature for aging for 30min.

[0093] Step 4: Add the second salt solution and precipitant solution prepared in step 2 into the reaction vessel equipped with mechanical stirring in a dropwise manner. During this process, control the pH at around 7.5, maintain the precipitation temperature at 75°C, and stir at a speed of 200 rpm / min. Finally, age the material at 75°C for 1 hour.

[0094] Step 5: After aging, the material is washed several times with deionized water and then filtered. The filter cake is dried and calcined at 380°C for 4 hours. Then, 1.5g of graphite and 10mL of water are added to granulate, press, crush, and sieve through a 4-6 mesh screen to obtain the gaseous aldehyde hydrogenation catalyst.

[0095] Comparative Example 2

[0096] A gas-phase aldehyde hydrogenation catalyst for alcohol production, the preparation method of which includes the following steps:

[0097] Step 1: Prepare a mixed metal solution using 94.5g zinc nitrate, 50.5g copper nitrate, and 1000mL deionized water;

[0098] Step 2: Prepare a mixed precipitant solution using 95.0g of anhydrous sodium carbonate and 1200mL of deionized water; add the mixed metal solution and mixed precipitant solution obtained in Step 1 to a reaction vessel equipped with a mechanical stirrer at a differential flow rate. Control the flow rate of the mixed metal solution at 40mL / min and the flow rate of the precipitant solution at 20mL / min. After the mixed metal solution has been completely added, adjust the flow rate of the precipitant solution to 30mL / min and add it dropwise until the pH is about 7.5. During this process, maintain the precipitation temperature at 70℃ and stir at 150rpm / min to complete the titration and neutralization of the material.

[0099] Step 3: Stir the aged material at 75℃ for 1 hour to completely neutralize the precipitate;

[0100] Step 4: After aging in step 3, the material is washed several times with deionized water at 75°C and then filtered. The filter cake is dried and calcined at 380°C for 4 hours. Then, 1.5g of graphite and 10mL of water are added to granulate, press, crush, and sieve through a 4-6 mesh screen to obtain the gaseous aldehyde hydrogenation catalyst.

[0101] The catalyst obtained above was applied to the gas-phase hydrogenation of octenal to octanol. The catalyst reduction temperature was 230℃, the reduction time was 10 h, the reduction pressure was 0.5 MPa, and the reducing gas space velocity was 1000 h⁻¹. -1 The hydrogenation reaction of octenal was carried out at a temperature of 180℃, a reaction pressure of 0.45 MPa, and a liquid hourly space velocity (LISH) of 0.4 h⁻¹. -1 The hydrogen / octenal molar ratio was 30, and the results of the hydrogenation reaction of octenal with catalyst are listed in Table 1.

[0102] Table 1

[0103]

[0104]

[0105] Table 2 Catalyst Pore Structure Parameters

[0106] sample <![CDATA[Specific surface area (m 2 / g)]]> <![CDATA[Pore volume (cm 2 / g)]]> Aperture (nm) Comparative Example 1 70 0.21 19 Comparative Example 2 58 0.20 18 Example 1 76 0.23 20 Example 2 84 0.26 19 Example 5 85 0.23 20 Example 7 90 0.29 19

[0107] The optimal embodiment of this invention is Example 7, in which the catalyst achieves 100% aldehyde hydrogenation activity, the octanol content in the product reaches 97.45 wt.%, and the C16 ester content is only 0.2%. The reduction of heavy components not only increases the octanol content but also reduces the energy consumption of distillation. Simultaneously, it can be observed that the hot spot temperature and C16 ester content in Examples 5, 6, 7, and 8 are relatively lower than those in the examples without the addition of a thermally conductive agent. This indicates that the addition of the thermally conductive agent can improve the heat transfer capacity of the catalyst, reduce the formation of heavy components, and significantly increase the octanol content. Comparing Examples 1 and 2 with Comparative Examples 1 and 2, and referring to Table 2, it can be seen that the preferential precipitation of aluminum and magnesium salts results in Examples 1, 2, 5, and 7 having higher specific surface areas and pore volumes. This is beneficial for heat transfer during the reaction process, reduces the formation of by-products, and increases the octanol content.

[0108] The embodiments described above merely illustrate specific implementation methods of this application, and while the descriptions are detailed and specific, they should not be construed as limiting the scope of protection of this application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the technical solution of this application, and these modifications and improvements all fall within the scope of protection of this application.

[0109] This background section is provided to generally present the context of the invention. The work of the currently named inventors, the work to the extent described in this background section, and aspects of this section that did not constitute prior art at the time of application are neither expressly nor impliedly acknowledged as prior art to the invention.

Claims

1. A method for preparing a highly selective gas-phase aldehyde hydrogenation catalyst for alcohol production, characterized in that, Includes the following steps: The first step is to mix the aluminum source, magnesium source, template agent and water to prepare the first salt solution, and then to precipitate the first salt solution and the precipitant in a co-current manner to form the first precipitate; The aluminum source has an aluminum concentration of 0.1–1 mol / L; the magnesium source has a magnesium concentration of 0.1–1 mol / L. The second step involves preparing a second salt solution by mixing copper nitrate, zinc nitrate, and water. Then, the second salt solution and the precipitant are added dropwise to the precipitate formed in the first step using a differential co-flow co-precipitation method. In the second salt solution, the concentration of zinc ions is 0.5–2 mol / L; the concentration of copper ions is 0.2–1 mol / L. The second step uses a differential co-flow co-precipitation method, in which the flow rate of the second salt solution is 15-30 mL / min and the flow rate of the precipitant solution is 5-20 mL / min. After the metal mixed solution is completely added, the flow rate of the precipitant solution is adjusted to 30 mL / min. The third step is to mix the co-precipitated mixture obtained in the first and second steps evenly, and then keep it warm and aged under stirring to ensure complete neutralization of the precipitate. The fourth step involves adding or not adding a heat-conducting agent to the aged precipitate, stirring until evenly mixed; then washing with water and filtering to obtain a filter cake, and drying the filter cake to obtain powder, which is then calcined at high temperature. The fifth step involves adding graphite and water to the calcined material for granulation, followed by tableting to obtain a catalyst, which is then used for the gas-phase hydrogenation of aldehydes to produce alcohols.

2. The method for preparing the highly selective gas-phase aldehyde hydrogenation catalyst for alcohol production according to claim 1, characterized in that: In the first step, the aluminum source is any one or a mixture of several of aluminum nitrate, sodium aluminate, and aluminum isopropoxide; the magnesium source is any one or a mixture of several of magnesium nitrate, magnesium carbonate, and basic magnesium carbonate; the template agent is any one of sorbitol, hexamethylenediamine, polyvinylpyrrolidone, and ethylenediaminetetraacetic acid, and the concentration of the template agent is 0.01 mol / L to 0.1 mol / L.

3. The method for preparing the highly selective gas-phase aldehyde hydrogenation catalyst for alcohol production according to claim 1, characterized in that: The precipitant used in both the first and second steps is an alkaline precipitant; the alkaline precipitant is selected from any one or a mixture of sodium carbonate, sodium bicarbonate and sodium hydroxide, with a concentration of 0.8 to 4 mol / L.

4. The method for preparing the highly selective gas-phase aldehyde hydrogenation catalyst for alcohol production according to claim 1, characterized in that, The conditions for the first step of co-precipitation and the second step of differential co-flow co-precipitation were as follows: co-precipitation temperature was room temperature to 75 ℃, rotation speed was 200-500 rpm, co-precipitation time was 20 to 70 minutes, and the final pH value of co-precipitation was 7.0 to 7.

5.

5. The method for preparing the highly selective gas-phase aldehyde hydrogenation catalyst for alcohol production according to claim 1, characterized in that: The aging temperature in the third step is 60 ℃~80 ℃, and the aging time is 1 h~2 h.

6. The method for preparing the highly selective gas-phase aldehyde hydrogenation catalyst for alcohol production according to claim 1, characterized in that: In the fourth step, before washing with water, a thermally conductive agent is added to the aged precipitate, stirred evenly and then washed with water; the added thermally conductive agent is any one or a mixture of several of MgAl alloy powder, SiCuAl alloy powder, Si3N4, BN and SiC.

7. The method for preparing the highly selective gas-phase aldehyde hydrogenation catalyst for alcohol production according to claim 1, characterized in that: In the fourth step, the high-temperature calcination temperature is 340–400 °C, and the calcination time is 4–6 h.

8. A highly selective gas-phase aldehyde hydrogenation catalyst for alcohol production prepared by any one of the methods described in claims 1-7, characterized in that: The catalyst contains 30%–40% copper oxide, 55%–69% zinc oxide, 1%–20% aluminum oxide, 1%–20% magnesium oxide, 0%–2% thermally conductive agent, and 1%–3% graphite by mass, for a total mass percentage of 100%.

9. The highly selective gas-phase aldehyde hydrogenation catalyst for alcohol production according to claim 8, characterized in that, The catalyst has a BET specific surface area of ​​40–100 m². 2 / g, pore volume 0.15~0.4 cm³ 3 / g, with an average pore radius of 10–20 nm.

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