A method for preparing metallic germanium

Abstract

The present invention relates to a method for preparing metallic germanium, comprising the following steps: causing gaseous germanium tetrachloride to undergo a first reduction reaction with hydrogen at 500-650°C, and then causing the obtained product to undergo a second reduction reaction with hydrogen at 180-350°C, so as to prepare metallic germanium. The method uses H2 to reduce GeCl4 in a two-step process to prepare metallic germanium, so that GeCl2 generated by the reaction of H2 and GeCl4 is further reduced to germanium, thereby improving the purity and yield of metallic germanium and reducing the doping of GeCl2.

Description

Technical Field

[0001] The invention relates to the technical field of germanium processing, and in particular to a method for preparing metallic germanium. Background Art

[0002] Reduced germanium is an important intermediate in the preparation of germanium single crystals, and its purity has a direct impact on the product quality of germanium single crystals. The current mainstream preparation process for reduced germanium is to hydrolyze high-purity germanium tetrachloride to generate germanium dioxide, and then reduce germanium dioxide with hydrogen to obtain reduced germanium. After decades of development, this process has a high degree of maturity, but the process is long, and there are many links that can cause product contamination. In addition, some trace metal impurities such as aluminum are not easy to remove in this process, making it difficult to prepare ultra-high purity germanium for detector-grade 13N germanium single crystals. Reduced germanium is also obtained by thermal decomposition of germanium, but germanium is extremely flammable and explosive, and has high safety risks.

[0003] In recent years, some domestic enterprises have begun to explore the preparation of high-purity germanium by hydrogen reduction of germanium tetrachloride. On the one hand, during the reduction process, some metal impurities in the chloride state can be removed because they do not participate in the reaction, such as aluminum; on the other hand, this method omits the hydrolysis process of germanium tetrachloride, shortens the process flow, and reduces the risk of pollution and germanium loss. The prior art discloses a method for directly preparing metallic germanium using germanium tetrachloride, and a reduced germanium ingot is obtained by the reduction reaction of germanium tetrachloride with hydrogen. However, in the experimental reaction, we found that GeCl2 was also generated, which seriously affected the purity of the reduced germanium ingot.

[0004] Therefore, developing a method for preparing metallic germanium to reduce the doping of GeCl2 and make it have high purity is an urgent problem to be solved by those skilled in the art. Summary of the invention

[0005] The purpose of the present invention is to overcome the shortcomings of the prior art and provide a method for preparing metallic germanium. The method uses H2 to reduce GeCl4 in a two-step process to prepare metallic germanium, so that GeCl2 generated by the reaction of H2 and GeCl4 is further reduced to metallic germanium, thereby improving the purity of metallic germanium and reducing the doping of GeCl2.

[0006] In order to achieve the above objectives, the present invention provides the following technical solutions.

[0007] A method for preparing metallic germanium comprises the following steps:

[0008] Gaseous germanium tetrachloride and hydrogen are subjected to a first reduction reaction at 500-650°C (for example, 500°C, 520°C, 540°C, 560°C, 580°C, 600°C, 620°C, 650°C), and the resulting product is subjected to a second reduction reaction with hydrogen at 180-350°C (for example, 180°C, 200°C, 220°C, 240°C, 260°C, 280°C, 300°C, 320°C, 340°C, 350°C), thereby preparing metallic germanium.

[0009] The preparation principle of the present invention is as follows:

[0010] GeCl4(g)+2H2(g)=Ge(s)+4HCl(g) (1)

[0011] GeCl4(g)+H2(g)=GeCl2(s)+2HCl(g) (1′)

[0012] GeCl4(g)+Ge(s)=2GeCl2(s) (1”)

[0013] GeCl2(s)+H2(g)=Ge(s)+2HCl(g) (2)

[0014] In the present invention, the reaction of GeCl4 and H2 has multiple side reactions. To ensure the quality of the reduction reaction, the reduction process is carried out in two steps. The first step is carried out at 500-650°C in the first temperature zone. Ge and GeCl2 microparticles are obtained by reaction (1)(1')(1") and are deposited in the second temperature zone as solid sediments under the guidance of air flow and the lower temperature (180-350°C) of the second temperature zone. In the second step, the GeCl2 in the solid sediment is further reduced with H2 to obtain metallic germanium. According to the Gibbs free energy change △G( Figure 1 ) It can be seen that when the temperature of reaction (1)(1')(1") is greater than 531℃, 500℃ and 480℃ respectively, △G is less than or equal to 0, and the reaction proceeds spontaneously in the forward direction. When the temperature is less than 350℃, △G of reaction (2) is less than 0, and the reaction can proceed spontaneously in the forward direction. Therefore, the reverse reaction of reaction (2) can be effectively controlled in the second temperature zone with lower temperature, which is beneficial to improve the purity and yield of metal germanium and reduce the doping of GeCl2.

[0015] In the present invention, the main components of the tail gas produced are GeCl4, GeCl2, Ge, HCl, and H2. After sedimentation, absorption, and drying treatment, GeCl2, Ge, GeCl4, and HCl can be recovered respectively, and the recycling of H2 can be achieved.

[0016] Preferably, the gaseous germanium tetrachloride is obtained by gasifying a germanium tetrachloride source by bubbling with hydrogen, and the molar ratio of the hydrogen to the germanium tetrachloride source is 2:1 to 100:1 (for example, 2:1, 3:1, 4:1, 5:1, 10:1, 15:1, 20:1, 25:1, 30:1, 35:1, 40:1, 45:1, 50:1, 55:1, 60:1, 65:1, 70:1, 75:1, 80:1, 85:1, 90:1, 95:1, 100:1), preferably 5:1 to 20:1. The hydrogen is continuously introduced into the first temperature zone with the gasified germanium tetrachloride, and the hydrogen undergoes a first reduction reaction with the gasified germanium tetrachloride.

[0017] Preferably, the temperature of the germanium tetrachloride source is controlled at 0-50°C (for example, 0°C, 5°C, 10°C, 15°C, 20°C, 25°C, 30°C, 35°C, 40°C, 45°C, 50°C).

[0018] Preferably, in the first reduction reaction, the molar ratio of the hydrogen to the gaseous germanium tetrachloride is 2:1 to 100:1, for example, (2:1, 3:1, 4:1, 5:1, 10:1, 15:1, 20:1, 25:1, 30:1, 35:1, 40:1, 45:1, 50:1, 55:1, 60:1, 65:1, 70:1, 75:1, 80:1, 85:1, 90:1, 95:1, 100:1), preferably 5:1 to 20:1.

[0019] Preferably, the molar ratio of the hydrogen introduced in the second reduction reaction to the hydrogen introduced in the first reduction reaction is 0.5:1 to 10:1, for example, it can be 0.5:1, 1:1, 2:1, 3:1, 4:1, 5:1, 6:1, 7:1, 8:1, 9:1, 10:1, preferably 1:1 to 3:1.

[0020] In some embodiments of the present invention, before the first reduction reaction, the process further comprises: introducing an inert gas to replace the gas in the reaction system. Before the reaction, the inert gas is introduced to replace the gas in the reaction system, and the air in the system can be replaced and removed from the system. The inert gas can be argon, helium, etc.

[0021] After the introduction of GeCl4 gas is stopped, unreacted GeCl2 remains in the reaction system. In some embodiments of the present invention, in order to improve the purity of metallic germanium, after the introduction of GeCl4 gas is stopped, the preparation method of the present invention further comprises: continuing to introduce hydrogen, and maintaining a constant temperature of 180-350°C (for example, 180°C, 200°C, 220°C, 240°C, 260°C, 280°C, 300°C, 320°C, 340°C, 350°C) for 1-6h (for example, 1h, 2h, 3h, 4h, 5h, 6h).

[0022] In some embodiments of the present invention, after the constant temperature maintenance is completed, it also includes: introducing an inert gas for gas replacement, and the replacement time is 0.5-2h (for example, 0.5h, 1h, 1.5h, 2h). The inert gas can be argon, helium, etc. After the replacement is completed, hydrogen is introduced to make the atmosphere in the entire reaction system hydrogen.

[0023] In some embodiments of the present invention, after the replacement is completed, it also includes: heating up to melt, then cooling down, and the melting temperature is 950-1050°C (for example, 950°C, 960°C, 970°C, 980°C, 990°C, 1000°C, 1010°C, 1020°C, 1030°C, 1040°C, 1050°C).

[0024] In the present invention, metallic germanium is melted in an inert atmosphere to cause a disproportionation reaction of the residual trace amount of GeCl2, thereby further removing GeCl2 and improving the purity of metallic germanium.

[0025] In some embodiments of the present invention, the purity of the germanium tetrachloride is above 99.9%, preferably above 99.99%, and more preferably above 99.999%.

[0026] In some embodiments of the present invention, the purity of the hydrogen is above 99.99%, preferably above 99.999%, and more preferably above 99.9999%.

[0027] In a specific embodiment of the present invention, high-purity argon is first used to replace the gas in the reaction system; then the argon is turned off and hydrogen is introduced to make the atmosphere in the entire system hydrogen; then the germanium tetrachloride source is gasified and brought into the reaction system by hydrogen bubbling, and a reduction reaction is carried out with hydrogen in two steps at a certain temperature; after the reaction is completed, hydrogen is continued to be introduced and the constant temperature is maintained for 1-6 hours; the hydrogen is turned off and argon is introduced to replace the gas in the reaction system; finally, the temperature is raised to 950-1050°C for melting, and the temperature is lowered to obtain metallic germanium.

[0028] The present invention melts metal germanium under an inert atmosphere to cause a disproportionation reaction of residual trace GeCl2, thereby further removing GeCl2.

[0029] Compared with the prior art, the present invention has the following beneficial effects:

[0030] 1. The present invention adopts H2 to reduce GeCl4 through a two-step method to prepare metallic germanium, so that GeCl2 generated by the reaction of H2 and GeCl4 continues to react with H2 to be removed, thereby improving the yield of metallic germanium and reducing the doping of GeCl2.

[0031] 2. The preparation method of the present invention allows compounds of trace metals such as Al, Mg, Mn, Pb, Ti, V, Zn, and In that do not react with H2 to directly enter the tail gas, and the prepared metallic germanium has a higher purity (99.999999%).

[0032] 3. The preparation method provided by the present invention does not involve the preparation process of germanium dioxide, has a simple process, reduces the discharge of high-salt wastewater, has fewer secondary pollution links, has simple tail gas components that are easy to recycle, and is green and environmentally friendly.

[0033] 4. The present invention melts metallic germanium under an inert atmosphere, which can cause residual trace amounts of GeCl2 to undergo a disproportionation reaction, thereby further removing GeCl2. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 It is the relationship between the Kipps free energy change (ΔG) and temperature of each reaction in the principle of the present invention. DETAILED DESCRIPTION

[0035] In order to make the content of the present invention easier to understand, the technical scheme of the present invention is further described below in conjunction with specific embodiments, but the present invention is not limited thereto. All technologies realized based on the above content of the present invention are included in the scope that the present invention is intended to protect. Unless otherwise specified, the raw materials and reagents used in the examples are all commercially available products. The reagents, instruments or operating procedures not recorded herein are all contents that can be routinely determined by a person of ordinary skill in the art.

[0036] Example 1

[0037] Weigh 500g of ultra-high purity germanium tetrachloride with a purity of 99.999999% in a germanium tetrachloride gasifier, use argon with a purity of 99.999% to exhaust the entire system for 1 hour, and then replace it with hydrogen with a purity of 99.999%. After the replacement is completed, the hydrogen is introduced into the germanium tetrachloride gasifier for bubbling, and the temperature of the germanium tetrachloride gasifier is controlled to be 20°C. The bubbling hydrogen is sequentially introduced into the first temperature zone and the second temperature zone of the synthesis furnace, and the temperatures of the first and second temperature zones are controlled to be 500°C and 220°C, respectively. , and directly introduce hydrogen with a purity of 99.999% into the second temperature zone, the molar ratio of hydrogen introduced into the first temperature zone to germanium tetrachloride is 10:1, and the molar ratio of hydrogen introduced into the second temperature zone to the first temperature zone is 1:1. After the germanium tetrachloride is completely gasified, continue to introduce hydrogen and keep the temperature constant for 3 hours to allow the unreacted yellow solid (germanium dichloride) to fully react. After the reaction is completed, argon is introduced to replace the hydrogen. After 0.5 hours, the temperature is raised to 1000°C for melting, and the temperature is lowered to obtain metallic germanium in the second temperature zone. The yield of metallic germanium is 96.8%.

[0038] Example 2

[0039] 300 g of ultra-high purity germanium tetrachloride with a purity of 99.999999% was weighed and placed in a germanium tetrachloride gasifier. The entire system was evacuated for 0.5 h using argon with a purity of 99.999%, and then replaced with hydrogen with a purity of 99.999%. After the replacement was completed, the hydrogen was introduced into the germanium tetrachloride gasifier for bubbling, and the temperature of the germanium tetrachloride gasifier was controlled to be 20° C. The bubbling hydrogen was sequentially introduced into the first temperature zone and the second temperature zone of the synthesis furnace, and the temperatures of the first and second temperature zones were controlled to be 550° C. and 250° C., respectively, and in the first temperature zone, the hydrogen was introduced into the second temperature zone, and the temperature of the first temperature zone was 250° C. and the temperature of the second temperature zone was 550° C. and 250° C., respectively. The second temperature zone is directly introduced with hydrogen of 99.999% purity. The molar ratio of hydrogen to germanium tetrachloride introduced in the first temperature zone is 5:1. The molar ratio of hydrogen introduced in the second temperature zone to the first temperature zone is 0.5:1. After the germanium tetrachloride is completely vaporized, the vaporization of germanium tetrachloride is stopped and hydrogen is continuously introduced. The temperature is kept constant for 3 hours to allow the unreacted yellow solid (germanium dichloride) to fully react. After the reaction is completed, argon is introduced to replace hydrogen. After 0.5 hours, the temperature is raised to 1000°C for melting. The metal germanium can be obtained by cooling in the second temperature zone. The yield of metal germanium is 97.1%.

[0040] Example 3

[0041] 450 g of ultra-high purity germanium tetrachloride with a purity of 99.999999% was weighed and placed in a germanium tetrachloride gasifier. The entire system was evacuated for 1.5 h using argon with a purity of 99.999%, and then replaced with hydrogen with a purity of 99.999%. After the replacement was completed, the hydrogen was introduced into the germanium tetrachloride gasifier for bubbling, and the temperature of the germanium tetrachloride gasifier was controlled to be 20° C. The bubbling hydrogen was sequentially introduced into the first temperature zone and the second temperature zone of the synthesis furnace, and the temperatures of the first and second temperature zones were controlled to be 580° C. and 300° C., respectively. The second temperature zone is directly introduced with hydrogen of 99.999% purity. The molar ratio of hydrogen to germanium tetrachloride introduced in the first temperature zone is 8:1. The molar ratio of hydrogen introduced in the second temperature zone to that in the first temperature zone is 1:1. After the germanium tetrachloride is completely vaporized, the vaporization of germanium tetrachloride is stopped and hydrogen is continuously introduced. The temperature is kept constant for 3 hours to allow the unreacted yellow solid (germanium dichloride) to fully react. After the reaction is completed, argon is introduced to replace hydrogen. After 0.5 hours, the temperature is raised to 1020°C for melting. The metal germanium can be obtained by cooling in the second temperature zone. The yield of metal germanium is 96.5%.

[0042] Example 4

[0043] 300 g of ultra-high purity germanium tetrachloride with a purity of 99.999999% was weighed and placed in a germanium tetrachloride gasifier. The entire system was evacuated for 2 h using argon with a purity of 99.999%, and then replaced with hydrogen with a purity of 99.999%. After the replacement was completed, the hydrogen was introduced into the germanium tetrachloride gasifier for bubbling, and the temperature of the germanium tetrachloride gasifier was controlled to be 20° C. The bubbling hydrogen was sequentially introduced into the first temperature zone and the second temperature zone of the synthesis furnace, and the temperatures of the first and second temperature zones were controlled to be 600° C. and 350° C., respectively, and in the second temperature zone, the hydrogen was introduced into the first temperature zone and the second temperature zone. The temperature zones are directly introduced with hydrogen of 99.999% purity. The molar ratio of hydrogen introduced into the first temperature zone to germanium tetrachloride is 10:1. The molar ratio of hydrogen introduced into the second temperature zone to the first temperature zone is 2:1. After the germanium tetrachloride is completely gasified, the gasification of germanium tetrachloride is stopped and hydrogen is continuously introduced. The temperature is kept constant for 3 hours to allow the unreacted yellow solid (germanium dichloride) to fully react. After the reaction is completed, argon is introduced to replace hydrogen. After 0.5 hours, the temperature is raised to 1030°C for melting. The metal germanium can be obtained by cooling in the second temperature zone. The yield of metal germanium is 97.4%.

[0044] Comparative Example 1

[0045] The method described in Example 1 was followed, except that the temperature of the first temperature zone was 400° C. No solids were generated in the reactor and the reaction did not proceed.

[0046] Comparative Example 2

[0047] The method described in Example 1 was followed, except that the temperature of the second temperature zone was 100° C. A large amount of dark yellow solid was deposited in the second temperature zone, and after melting, partially reduced germanium was obtained, but the yield was less than 70%, and a large amount of germanium tetrachloride was found in the tail gas.

[0048] Comparative Example 3

[0049] The method described in Example 1 was followed, except that the molar ratio of hydrogen to germanium tetrachloride introduced into the first temperature zone was 1:1. A large amount of germanium tetrachloride droplets were generated in the air inlet pipe of the first temperature zone, and the amount of solid deposition in the second temperature zone was significantly reduced, the germanium tetrachloride content in the tail gas was greatly increased, and the yield of metallic germanium was about 75%.

[0050] Comparative Example 4

[0051] 500g of ultra-high purity germanium tetrachloride with a purity of 99.999999% was weighed and placed in a germanium tetrachloride gasification device. The entire system was evacuated for 1 hour using argon with a purity of 99.999%, and then replaced with hydrogen with a purity of 99.999%. After the replacement was completed, the hydrogen was introduced into the germanium tetrachloride gasification device for bubbling, and the temperature of the germanium tetrachloride gasification device was controlled to be 20°C. The bubbling hydrogen was introduced into a synthesis furnace at 500°C, and the molar ratio of the introduced hydrogen to germanium tetrachloride was 10:1. After all the germanium tetrachloride was gasified, the reaction was stopped, and argon was introduced to replace the hydrogen. After 0.5h, a solid deposit was obtained in the low temperature area of ​​the furnace body, and the temperature was raised to 1000°C for melting to obtain metallic germanium. The yield of metallic germanium was less than 60%.

[0052] Germanium metal purity detection

[0053] The metallic germanium obtained in Example 1 is detected by ICP-MS, and the purity of the metallic germanium can reach 99.999999%.

[0054] Test items content Test items content Al, μg / kg <0.1 Mg, μg / kg <0.1 As, μg / kg <0.1 Mn, μg / kg <0.1 Ca, μg / kg 0.5 Na, μg / kg 0.2 Co, μg / kg <0.1 Ni, μg / kg <0.1 Cr, μg / kg <0.1 Pb, μg / kg <0.1 Cu, μg / kg 0.2 Ti, μg / kg <0.1 Fe, μg / kg 0.3 V, μg / kg <0.1 In, μg / kg <0.1 Zn, μg / kg <0.1 K, μg / kg 0.5

[0055] The above is only a preferred specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed by the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention shall be based on the protection scope of the claims.

Claims

1. A method for preparing metallic germanium, characterized in that: The following steps are involved: The gaseous germanium tetrachloride is subjected to a first reduction reaction with hydrogen at 500-650°C, and the obtained product is subjected to a second reduction reaction with hydrogen at 180-350°C to obtain metallic germanium; In the first reduction reaction, the molar ratio of the hydrogen to the gaseous germanium tetrachloride is 2:1 to 100:1, the purity of the germanium tetrachloride is greater than 99.999%, and the purity of the hydrogen is greater than 99.99%; The purity of the metallic germanium reaches 99.999999%.

2. The preparation method according to claim 1, characterized in that: The gaseous germanium tetrachloride is obtained by gasifying a germanium tetrachloride source by bubbling hydrogen, and the molar ratio of the hydrogen to the germanium tetrachloride source is 2:1-100:

1.

3. The preparation method according to claim 2, characterized in that: The molar ratio of the hydrogen to the germanium tetrachloride source is 5:1 to 20:

1.

4. The preparation method according to claim 2, characterized in that: The temperature of the germanium tetrachloride source is controlled at 0-50°C.

5. The preparation method according to claim 1 or 2, characterized in that: In the first reduction reaction, the molar ratio of the hydrogen to the gaseous germanium tetrachloride is 5:1 to 20:

1.

6. The preparation method according to claim 1 or 2, characterized in that: The molar ratio of the hydrogen introduced in the second reduction reaction to the hydrogen introduced in the first reduction reaction is 0.5:1-10:

1.

7. The preparation method according to claim 6, characterized in that: The molar ratio of the hydrogen introduced in the second reduction reaction to the hydrogen introduced in the first reduction reaction is 1:1 to 3:

1.

8. The preparation method according to claim 1 or 2, characterized in that: Before the first reduction reaction, the method further comprises: introducing an inert gas to replace the gas in the reaction system; after the replacement is completed, introducing hydrogen to make the atmosphere in the entire reaction system hydrogen.

9. The preparation method according to claim 1 or 2, characterized in that: After the introduction of the gaseous germanium tetrachloride is stopped, the method further comprises: continuing to introduce hydrogen and maintaining a constant temperature at 180-350° C. for 1-6 hours.

10. The preparation method according to claim 9, characterized in that: After the constant temperature maintenance is completed, the method further comprises: introducing an inert gas to perform gas replacement, wherein the replacement time is 0.5-2 hours.

11. The preparation method according to claim 10, characterized in that: After the replacement is completed, the process further includes: heating up to melt, and then cooling down, wherein the melting temperature is 950-1050°C.

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