Production method for raney metal alloy powder, and related device and use

Abstract

A method for safely and stably producing a Raney metal alloy powder (12) by means of a water atomization method. In the method, a gas is introduced so as to reduce the hydrogen concentration until below a lower explosive limit, and hydrogen can be efficiently guided to an exhaust conduit by means of a gas discharge apparatus. Further provided are a Raney metal alloy powder (12) obtained by means of the method and the use of the Raney metal alloy powder (12) in the preparation of a catalyst, and a device for the method.

Description

Raney metal alloy powder production methods, related equipment and applications Technical Field

[0001] This invention relates to a method for producing Raney metal alloy powder by water atomization, the Raney metal alloy powder obtained therefrom, the use of the alloy powder in the preparation of catalysts, and related apparatus. Background Technology

[0002] Raney metal catalysts have advantages such as low cost, high process controllability, and mature technology, and are widely used in various organic synthesis hydrogenation reactions. Traditional production methods for Raney metal catalysts involve steps such as high-temperature melting, rapid cooling into strips, crushing, grinding, sieving, and activation. During the crushing process, equipment such as jaw crushers and Raymond mills are required to further crush, grind, and sieve the rapidly cooled alloy strips longer than 3 cm. This process is not only energy-intensive but also involves harsh operating conditions.

[0003] If existing powder-making technologies such as gas atomization and water atomization are used, the liquid metal can be broken and cooled to solidify into fine powder in one step, eliminating the need for crushing and grinding processes.

[0004] However, the existing gas atomization method has a low specific heat of gas, and its operating cost and equipment investment are nearly 10 times higher than those of the water atomization method, making it unsuitable for large-scale production.

[0005] The current water atomization method used in the production of Raney metal alloys faces safety risks because Raney metal alloys contain more than 40% aluminum, which readily reacts with water to produce hydrogen gas. If the atomizing canister is filled with air, the hydrogen concentration inside could instantly reach the explosive limit of 4.0-75.6% by volume. Even if the atomizing canister is filled with nitrogen, hydrogen gas can easily escape into the operating environment through the gap between the atomizing canister and the leaking package.

[0006] Patent CN104227007A describes an industrial-scale production of water-atomized aluminum powder by controlling the reaction between aluminum powder and water with the addition of inhibitors to reduce hydrogen production. The inhibitors used in this invention are acetic acid or oxalic acid, controlling the pH of the atomized water to 4.0-5.0 to suppress the reaction between aluminum powder and water. However, for Raney metal catalysts, especially Raney nickel catalysts, nickel is the active metal. If this method is used, the low pH will cause a certain degree of nickel loss, damaging the alloy structure and severely affecting the catalyst's lifespan. Summary of the Invention

[0007] To address the technical problems existing in the prior art, the present invention aims to provide a method for safely and stably producing Raney metal alloy powder via water atomization. This method involves introducing gas to dilute the hydrogen concentration below the lower explosive limit, while a gas exhaust device efficiently guides the hydrogen to an exhaust pipe. Specifically, a flame arrester installed at the top of the exhaust pipe further ensures the safe deflection of hydrogen out of the system, preventing potential safety hazards. The present invention also provides Raney metal alloy powder obtained by the described method, its use in catalyst preparation, and related apparatus.

[0008] Here, "Raney metal alloy" refers to an alloy containing aluminum and other catalytically active metals, which preferably include one or more metals or metalloids selected from Group IIA (e.g., Mg), Group IIIA (e.g., B, Ga), Group IVA (e.g., Ge, Sn, Pb), Group VA (e.g., Sb), Group IB (e.g., Cu), Group IIB (e.g., Zn, Cd), Group IIIB (e.g., Sc, Y, La-Lu), Group IVB (e.g., Ti, Zr), Group VB (e.g., V, Nb), Group VIB (e.g., Cr, Mo, W), Group VIIB (e.g., Mn, Re), and Group VIIIB (e.g., Fe, Co, Ni), more preferably one or more of Ni, Co, Cu, Mo, Sn, Zn, Fe, V, Mn, Sm, Ti, Cr, Ce, La, Ga, and Mg, particularly one or more of Ni, Co, Cu, Mo, Fe, Cr, Ti, and Mg.

[0009] The particle size of the "powder" is preferably 4-900 micrometers with a D50, and more preferably 8-450 micrometers with a D50.

[0010] Specifically, the present invention provides a method for producing Raney metal alloy powder by water atomization, which includes the following steps:

[0011] (1) Provides a container for containing molten metal with a hole at the bottom and an atomizing canister containing water located below it, wherein the atomizing canister is equipped with a high-pressure water pump and an exhaust device is installed on one side above the horizontal plane of the atomizing canister, and an inlet gas device is installed on the other side opposite to the exhaust device.

[0012] (2) Aluminum and other catalytically active metals are heated and melted to obtain a molten metal mixture;

[0013] (3) Turn on the high-pressure water pump, the exhaust device and the gas introduction device. They can be turned on simultaneously or in sequence.

[0014] (4) The molten metal mixture is added to the preheated container containing the molten metal, enters the atomizing can through the hole, and is pulverized by the high-pressure water generated by the high-pressure water pump to obtain Raney metal alloy powder.

[0015] Steps (2) and (3) can be interchanged.

[0016] The flow rate of the introduced gas is 1050 Nm³. 3 / h or more.

[0017] The atomizing canister can be designed as a closed or open structure.

[0018] The container for holding the molten metal is, for example, a leaky bag with a hole at the bottom.

[0019] The diameter of the bottom hole (e.g., the diameter of the drain hole) of the container holding the molten metal is adjusted according to the particle size requirements of the downstream application. For example, the diameter of the bottom hole (e.g., the diameter of the drain hole) of the container holding the molten metal is 2-20 mm, preferably 6-12 mm.

[0020] The exhaust equipment is, for example, an induced draft fan, a chimney, etc.

[0021] The introduced gas (also known as the "protective gas") can be any suitable gas that does not affect the metal alloy, such as a gas selected from air, nitrogen, argon, oxygen or a mixture of two or more thereof, preferably a gas selected from air, nitrogen, oxygen, a mixture of oxygen and nitrogen, and a mixture of oxygen and argon.

[0022] The flow rate of the introduced gas is adjusted according to the particle size requirements of the downstream application scenario (e.g., adjusted based on the volume of the atomizing can to ensure that the hydrogen concentration in the atomizing can is below the lower explosive limit, e.g., 4.0% by volume), and is preferably 1200 Nm. 3 / h or higher, preferably 1600Nm 3 / h or higher, and even better 1800Nm 3 / h and above, especially 2200Nm 3 / h or higher, for example, 2600Nm 3 / h or more.

[0023] The temperature at which aluminum and other catalytically active metals are heated to melt is, for example, 200-3000°C, and the heating time is, for example, 10-90 min, preferably 40-60 min.

[0024] The jet pressure of the water generated by the high-pressure water pump is adjusted according to the particle size requirements of the downstream application. The jet pressure of the water generated by the high-pressure water pump is preferably 3-15 MPa, and more preferably 5-8 MPa.

[0025] In one embodiment, the water jet angle formed between the molten metal flow and the water flow is preferably 0-90 degrees, more preferably 30-60 degrees.

[0026] The high-pressure water pump, for example, is mounted on top of the atomizing canister, and the high-pressure water it generates pulverizes the molten metal stream flowing down from the bottom hole of the container containing the molten metal.

[0027] In step (4), the Raney metal alloy powder obtained by high-pressure water pulverization, for example, falls into the water in the atomizing tank, and can be separated from the water by vacuum filtration, centrifugation or sedimentation to obtain the Raney metal alloy powder.

[0028] In step (4), the concentration of hydrogen in the gas discharged from the exhaust device can be determined by using an online hydrogen purity analyzer, thereby determining the concentration of hydrogen in the atomizing can, which is, for example, less than 4.0% by volume, preferably less than 3.0% by volume, and more preferably less than 2.5% by volume.

[0029] The height of the water level in the atomizing can is selected based on the requirements of not affecting the flow of molten metal alloys pulverized by high-pressure water and the introduction of gas. For example, the height of the water level is 10-90% of the height of the atomizing can.

[0030] The Raney metal alloy powder may be optionally dried.

[0031] This invention also relates to the use of the obtained Raney metal alloy powder in the preparation of Raney metal catalysts. The Raney metal alloy powder can be further activated, for example, by activation with an alkali, to form a Raney metal catalyst. The alkali is, for example, a sodium hydroxide solution or a potassium hydroxide solution. The alkali can be used in the form of an alkaline solution, with a concentration of 15-30% by weight, preferably 20-25% by weight; the reaction temperature with the alkaline solution can be 50-100°C, preferably 80-100°C; and the reaction time can be 0.8-5 hours, preferably 2-5 hours.

[0032] Accordingly, the present invention also relates to an apparatus for the above-described method of producing Raney metal alloy powder, comprising a container for containing molten metal with a hole at the bottom, an atomizing tank containing water located below the container, and an online hydrogen purity analyzer, wherein the atomizing tank is equipped with a high-pressure water pump, and an exhaust device is installed on one side above the horizontal plane of the atomizing tank, and a gas introduction device is installed on the other side opposite to the exhaust device.

[0033] The advantages of this invention are as follows:

[0034] 1. By introducing gas to dilute the hydrogen during the atomization process, the hydrogen concentration in the entire atomizing can is significantly reduced, keeping it below the lower explosive limit of hydrogen and ensuring operational safety.

[0035] 2. After atomization, the metallic components in the aluminum and alloy within the atomizing can may react with water to continue generating hydrogen. Since the container holding the molten metal is empty, a gas exhaust device efficiently guides the hydrogen to an exhaust pipe to prevent it from escaping through a leak in the container holding the molten metal. Specifically, a flame arrester installed at the top of this exhaust pipe further ensures the safe removal of hydrogen from the system, preventing potential safety hazards. Attached Figure Description

[0036] Figure 1 is a schematic diagram of a specific production device for Raney metal alloy powder, where the markings have the following meanings: 1. Leaking bag; 2. Leaking hole; 3. Molten metal; 4. Nozzle; 5. Air; 6. Spray angle; 7. Exhaust fan; 8. Online hydrogen purity analyzer; 9. Flame arrester; 10. Atomizing tank; 11. Water; 12. Raney metal alloy powder.

[0037] The production method of the Raney metal alloy in this invention is explained below with reference to Figure 1:

[0038] 1. In the production unit shown in Figure 1, the induced draft fan 7 is turned on to introduce air 5 from the air pipeline into the atomizing canister. The hydrogen concentration in the exhaust gas is tested using an online hydrogen purity analyzer 8. The hydrogen and gas are then guided out of the system through a flame arrester 9 installed at the top of the pipeline.

[0039] 2. Turn on the high-pressure water pump so that high-pressure water is sprayed out from nozzle 4.

[0040] 3. Pour the molten alloy 3 into the sluice box 1. The sluice box has an opening 2 at the bottom. The molten alloy 3 falls through the opening 2 and is broken and cooled down by the high-pressure water sprayed from the nozzle 4 at a certain spray angle 6 and in a single or multiple or ring manner, forming Raney metal alloy powder 12. Detailed Implementation

[0041] The present invention will be further described with reference to the following embodiments, but the present invention is not limited to these embodiments.

[0042] Example 1

[0043] Preparation of Raney nickel alloy powder

[0044] 1) Using the apparatus shown in Figure 1, 65 kg Al, 39 kg Ni and 26 kg Mo were added to a medium-frequency power induction heating melting furnace according to the composition ratio in Table 1.

[0045] 2) Turn on the heating system and heat to 1500℃ for 45 minutes to melt the metal and form a molten metal mixture, while heating the swivel.

[0046] 3) Turn on the induced draft fan and open the gas inlet pipe on the opposite side to introduce protective gas (air) into the atomizing can through the induced draft fan. The volume of the atomizing can is 5m³. 3 The flow rate of the protective gas is 1800 Nm. 3 / h.

[0047] 4) Turn on the high-pressure water pump so that the high-pressure tap water is sprayed out of the nozzle at a 45-degree angle, with a flow rate of 10.4 m³ / min. 3 / h, the pressure of the high-pressure water is 7MPa.

[0048] 5) Pour the molten metal mixture into a sieve bag, allowing it to flow into the atomizing can through a 10mm diameter sieve. The mixture is then pulverized by high-pressure water jet to obtain Raney nickel alloy powder. This powder falls into the water within the atomizing can, is filtered, and dried to obtain Raney nickel alloy powder. The D50 value was determined to be 80 micrometers using a laser particle size analyzer.

[0049] The online hydrogen purity analyzer tested the maximum hydrogen concentration in the exhaust gas to be 2.2% by volume.

[0050] Example 2

[0051] The composition ratio of the Raney metal alloy powder raw material was changed from that described in Example 1 to 65 kg Al, 39 kg Ni, 23 kg Fe, and 3 kg Cr. The protective gas was changed from air to nitrogen, and the flow rate of the protective gas was 2200 Nm³. 3 / h. Other conditions are the same as in Example 1.

[0052] The online hydrogen purity analyzer tested the maximum hydrogen concentration in the exhaust gas to be 1.9% by volume.

[0053] Example 3

[0054] The composition ratio of the Raney metal alloy powder raw material was changed from that described in Example 1 to 65 kg Al, 52 kg Ni, and 13 kg Ti. The protective gas was changed from air to 50% oxygen + 50% nitrogen, and the protective gas flow rate was 2600 Nm. 3 / h. Other conditions are the same as in Example 1.

[0055] The online hydrogen purity analyzer tested the maximum hydrogen concentration in the exhaust gas to be 1.7% by volume.

[0056] Example 4

[0057] The composition ratio of the Raney metal alloy powder raw material was changed from that described in Example 1 to 65 kg Al, 46 kg Co, 18 kg Ni, and 1 kg Cr. The protective gas was changed from air to 50% oxygen + 50% argon, and the protective gas flow rate was 2800 Nm. 3 / h. Other conditions are the same as in Example 1.

[0058] The online hydrogen purity analyzer tested the maximum hydrogen concentration in the exhaust gas to be 1.3% by volume.

[0059] Example 5

[0060] The composition ratio of the Raney metal alloy powder raw material was changed from that described in Example 1 to 65 kg Al and 65 kg Cu. The protective gas was changed from air to oxygen, and the induced draft fan flow rate was adjusted to 3000 Nm³. 3 / h. Other conditions are the same as in Example 1.

[0061] The online hydrogen purity analyzer tested the maximum hydrogen concentration in the exhaust gas to be 1.3% by volume.

[0062] Example 6

[0063] The composition ratio of the Raney metal alloy powder raw material was changed from that described in Example 1 to 65 kg Al and 65 kg Fe. The induced draft fan flow rate was adjusted to 2100 Nm³. 3 / h. Other conditions are the same as in Example 1.

[0064] The online hydrogen purity analyzer tested the maximum hydrogen concentration in the exhaust gas to be 1.9% by volume.

[0065] Example 7

[0066] The composition ratio of the Raney metal alloy powder raw material was changed from that described in Example 1 to 65 kg Al, 49 kg Ni, 9 kg Fe, and 7 kg Mg. The exhaust method was changed from an induced draft fan to a chimney, and the protective gas flow rate was 2400 Nm³. 3 / h. Other conditions are the same as in Example 1.

[0067] The online hydrogen purity analyzer tested the maximum hydrogen concentration in the exhaust gas to be 1.6% by volume.

[0068] Comparative Example 1

[0069] The airflow was reduced from 1800 Nm as described in Example 1. 3 / h changed to 800Nm 3 / h. Other conditions are the same as in Example 1.

[0070] The maximum hydrogen concentration in the exhaust gas measured by the online hydrogen purity analyzer was 4.9% by volume.

[0071] Comparative Example 2

[0072] The airflow was reduced from 1800 Nm as described in Example 1. 3 / h changed to 1000Nm 3 / h. Other conditions are the same as in Example 1.

[0073] The online hydrogen purity analyzer tested the maximum hydrogen concentration in the exhaust gas to be 4.0% by volume.

[0074] Comparative Example 3

[0075] The exhaust method was changed from the induced draft fan described in Example 2 to no exhaust, with a protective gas flow rate of 40 Nm. 3 / h. The other steps are the same as in Example 2.

[0076] The maximum hydrogen concentration in the exhaust gas measured by the online hydrogen purity analyzer was 51.0% by volume.

[0077] Table 1

Claims

1. A process for producing Raney metal alloy powder by water atomization, comprising the steps of: (1) providing a container for holding molten metal with a hole in the bottom and an atomization tank filled with water below, wherein the atomization tank is equipped with a high-pressure water pump and an exhaust device on one side above the water level of the atomization tank, and a gas introduction device on the other side opposite to the exhaust device; (2) heating and melting aluminum and other catalytically active metals to obtain a molten metal mixture; (3) turning on the high-pressure water pump, the exhaust device and the gas introduction device, which can be turned on simultaneously or sequentially; (4) adding the molten metal mixture into the preheated container for holding molten metal through the hole into the atomization tank, and pulverizing by high-pressure water generated by the high-pressure water pump to obtain Raney metal alloy powder; wherein the order of steps (2) and (3) can be exchanged, wherein the flow rate of the introduced gas is 1050 Nm 3 / h or more.

2. The process according to claim 1, wherein Raney metal alloy means an alloy containing aluminum and other catalytically active metals, which preferably include one or more metals or metalloids from group IIA (e.g. Mg), group IIIA (e.g. B, Ga), group IV A (e.g. Ge, Sn, Pb), group VA (e.g. Sb), group IB (e.g. Cu), group IIB (e.g. Zn, Cd), group IIIB (e.g. Sc, Y, La-Lu), group IVB (e.g. Ti, Zr), group VB (e.g. V, Nb), group VIB (e.g. Cr, Mo, W), group VII B (e.g. Mn, Re) and group VIII (e.g. Fe, Co, Ni), more preferably one or more of Ni, Co, Cu, Mo, Sn, Zn, Fe, V, Mn, Sm, Ti, Cr, Ce, La, Ga and Mg, especially one or more of Ni, Co, Cu, Mo, Fe, Cr, Ti and Mg, and / or the particle size of the "powder" is D50 of 4-900 microns, preferably D50 of 8-450 microns.

3. The process according to claim 1 or 2, wherein the atomization tank can be designed as a closed or open structure, and / or the container for holding molten metal is a bag with a hole in the bottom, and / or the diameter of the hole (e.g. the diameter of the hole in the bag) at the bottom of the container for holding molten metal is 2-20 mm, preferably 6-12 mm, and / or the exhaust device is, for example, an air blower, a vacuum pump, a chimney, etc.

4. The process according to any one of claims 1-3, wherein the introduced gas is any suitable gas that does not affect the metal alloy, for example, selected from air, nitrogen, argon, oxygen or a mixture of two or more thereof, preferably selected from air, nitrogen, oxygen, a mixture of oxygen and nitrogen, and a mixture of oxygen and argon, and / or The flow rate of the introduced gas is 1200 Nm 3 / h or more, more preferably 1600 Nm 3 / h or more, still more preferably 1800 Nm 3 / h or more, particularly 2200 Nm 3 / h or more, for example 2600 Nm 3 / h or more.

5. The process according to any one of claims 1-4, wherein in step (4), the angle of water jet formed between the stream of the molten metal mixture and the water stream is preferably 0-90 degrees, more preferably 30-60 degrees, and / or In step (4), the concentration of hydrogen in the discharged gas is less than 4.0 vol%, preferably less than 3.0 vol%, more preferably less than 2.5 vol%, and / or The height of the level in the atomizing tank is 10-90% of the height of the atomizing tank, and / or The injection pressure of the water produced by the high-pressure water pump is 5-10 MPa, more preferably 5-8 MPa, and / or In step (4), the high-pressure water pulverization causes the Raney metal alloy powder to fall into the water in the atomizing tank, and the Raney metal alloy powder is obtained separately from the water.

6. The method according to any one of claims 1-5, wherein The Raney metal alloy powder is further activated, for example by activation with a base, to form a Raney metal catalyst; the base can be used in the form of a base solution, and the concentration thereof can be 15-30 wt%, preferably 20-25 wt%; the reaction temperature with the base solution can be 50-100°C, preferably 80-100°C; and the reaction time can be 0.8-5 hours, preferably 2-5 hours.

7. An apparatus for the method according to any one of claims 1-6, comprising a vessel containing molten metal with a hole in the bottom, an atomizing tank containing water below it, and an on-line hydrogen purity analyzer, wherein the atomizing tank is provided with a high-pressure water pump, and one side above the level of the atomizing tank is provided with a gas discharge device, and the other side opposite the gas discharge device is provided with a gas introduction device.

8. A Raney metal alloy powder obtained by the method according to any one of claims 1-6.

9. Use of the Raney metal alloy powder according to claim 8 for the preparation of a Raney metal catalyst.

Images