TW201905241A - Method for electrochemically producing decane - Google Patents

Abstract

Provided is a method for electrochemically producing germane by applying an electric current to a germanium compound-containing electrolytic solution in an electrochemical cell having a barrier membrane, an anode, and a palladium-containing cathode to cause the generation of germane in the cathode.

Description

Method for producing germane by electrochemical method

The present invention relates to a method for electrochemically producing germane.

In the past, high-speed and low-power consumption of semiconductor devices can be achieved by miniaturization of the device, but as a technology for further high-speed and low-power consumption, strained silicon such as SiGe substrates has been prepared. By the attention. As a raw material when manufacturing the SiGe substrate, germane (GeH ₄ ) is used. As the use of SiGe substrates increases, the amount of GeH ₄ used is expected to increase.

As a method for producing such GeH ₄ , for example, Patent Document 1 describes that GeH ₄ can be electrochemically produced with a high current efficiency by using a Cu alloy or a Sn alloy as a cathode.

Furthermore, Non-Patent Document 1 describes the results of screening Pt, Zn, Ti, graphite, Cu, Ni, Cd, Pb, and Sn as cathodes used in the electrochemical production of GeH ₄ from the viewpoints of current efficiency and pollution, Cd or Cu is most suitable.

In addition, Non-Patent Document 2 discloses the results of investigating a plurality of cathodes as cathodes used for electrochemical production of GeH _4. When Hg is used as the cathode, the hydrogenation rate becomes 99% or more. [Prior Art Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Application Publication No. 2012-52234 [Non-Patent Document]

[Non-Patent Document 1] Turygin et. Al., Inorganic Materials, 2008, vol.44, No.10, pp.1081-1085 [Non-Patent Document 2] Djurkovic et. Al., Glanik Hem. Drustva, Beograd, 1961 , vol.25 / 26, pp.469-475

[Questions to be Solved by the Invention]

The cathode (bronze manufactured by McMaster-Carr) used in the embodiment of the aforementioned Patent Document 1 is difficult to apply by a method such as plating or coating, in which only effective elements exist on the surface, and is not advantageous for industrial production of GeH ₄ . In addition, when Cd or Cu used in the aforementioned Non-Patent Document 1 is used as a cathode, the current efficiency is lowered due to long-term reaction, which is disadvantageous for industrial continuous reactions. Furthermore, the cathode (Hg) used in the aforementioned Non-Patent Document 2 is highly toxic and cannot be used for industrial reactions.

One embodiment of the present invention provides a method for electrochemically manufacturing GeH ₄ with a stable current efficiency over a long period of time. [Means to solve the problem]

As a result of an active review by the present inventors to solve the aforementioned problems, they found that the aforementioned problems can be solved by the following manufacturing methods, etc., and thus completed the present invention. The configuration examples of the present invention are as follows.

[1] A method for electrochemically producing germane, which is based on an electrochemical cell having a separator, an anode, and a cathode containing palladium, energizing an electrolyte containing a germanium compound, and producing germane at the cathode.

[2] The method for producing germane according to [1], wherein the aforementioned electrolytic solution is an electrolytic solution containing germanium dioxide and an ionic substance. [3] The method for producing germane according to [2], wherein the ionic substance is potassium hydroxide or sodium hydroxide. [4] The method for producing germane according to [2] or [3], wherein the aforementioned ionic substance is potassium hydroxide, and the potassium hydroxide concentration in the aforementioned electrolytic solution is 1 to 8 mol / L.

[5] The method for producing germane according to any one of [1] to [4], wherein the cathode current density when the aforementioned current is applied is 30 to 500 mA / cm ² . [6] The method for producing germane according to any one of [1] to [5], wherein the reaction temperature when the aforementioned germane is produced is 10 to 100 ° C. [Inventive effect]

According to one embodiment of the present invention, GeH ₄ can be electrochemically manufactured for a long period of time with stable current efficiency.

A method for producing an electrochemical <<>> GeH ₄ of the electrochemical method of manufacturing a shape of a GeH ₄ embodiment of the present invention (hereinafter, also referred to as "the present method") based on a septum, an electrochemical cell comprising a cathode and an anode of the palladium , the energization of the electrolytic solution of the compound containing germanium, to produce a cathode GeH _4, electrochemically manufactured GeH _4. According to the present invention, GeH ₄ can be efficiently electrochemically manufactured with a stable current efficiency for a long period of time. Therefore, by using GeH ₄ obtained by this method, a SiGe substrate can also be efficiently produced.

In order to exert the aforementioned effects, the method can be preferably used for industrial continuous reactions. As such an industrial reaction, for example, a reaction having a scale of an electrolytic solution capacity of 500 to 2500 L, a number of units of 30 to 150, and a current of 100 to 300 A is used. In addition, as the aforementioned continuous reaction, it means that the reaction is preferably performed continuously for 20 to 200 hours, more preferably for 30 to 120 hours.

According to this method, GeH ₄ can be manufactured with a better current efficiency of 10 to 90% and more preferably 12 to 40%. In addition, according to this method, for example, when the continuous reaction is performed for 30 hours, when the current efficiency at a reaction time of 10 hours is set to 100%, the current efficiency at 30 hours of the reaction time is preferably maintained at Above 95%, more preferably above 99%. The current efficiency can be specifically measured by the method described in the following examples.

<Electrochemical cell> As the electrochemical cell, a separator, an anode, and the cathode are not particularly limited, and conventionally known cells can be used. As a specific example of the unit, a unit that uses a separator to separate an anode chamber including an anode and a cathode chamber including a cathode is used.

<Cathode> The cathode is not limited as long as it contains Pd.阴极 The cathode can be an electrode made of metal Pd or an electrode made of Pd-based alloy containing Pd as the main component, or an electrode plated or coated with metal Pd or Pd alloy. (2) Examples of the aforementioned electrode to be plated or coated include an electrode to be plated or coated with metal Pd or a Pd alloy on a substrate such as Ni. Among these, since metal Pd is expensive, it is preferably an electrode that is plated or coated with metal Pd or Pd alloy based on cost.

The shape of the cathode is not particularly limited, and may be any of a plate shape, a column shape, and a hollow shape. In addition, the size, surface area, etc. of the foregoing cathode are not particularly limited.

<Anode> The anode is not particularly limited, and any anode that has been conventionally used in the electrochemical production of GeH ₄ may be used, but an electrode made of a conductive metal such as Ni, Pt, or the like is preferred. An electrode made of an alloy containing a main component is preferably an electrode made of Ni based on cost. In addition, the anode and the cathode may be electrodes that are plated or coated with the conductive metal or an alloy containing the metal. In addition, the shape, size, surface area, and the like of the anode are also not particularly limited similarly to the cathode.

<Separator> The separator is not particularly limited as long as it is used as a separator that can be used to separate the anode chamber and the cathode chamber, which has been conventionally used in electrochemical cells.此种 As such a separator, various electrolyte membranes or porous membranes can be used. Examples of the electrolyte membrane include polymer electrolyte membranes such as ion-exchange solid polymer electrolyte membranes, and specifically, NAFION (registered trademark) 115, 117, NRE-212 (manufactured by SIGMA ALDRICH), and the like. As the porous film, porous glass, porous alumina, porous titanium oxide, and other porous ceramics, porous polyethylene, and porous polymers such as porous propylene can be used.

In one embodiment of the present invention, since the electrochemical cell is divided into an anode chamber and a cathode chamber by a diaphragm, the O ₂ gas generated at the anode and the GeH ₄ generated at the cathode are not mixed, and can be independent from each electrode chamber. Take out the exit. When O ₂ gas and GeH _{4 are} mixed, O ₂ gas and GeH ₄ react, and the yield of GeH ₄ tends to decrease.

<An electrolytic solution containing a germanium compound> This method is to produce GeH ₄ from an electrolytic solution containing a germanium compound. The electrolytic solution is preferably an aqueous solution.

The germanium compound is preferably GeO ₂ . The higher the concentration of GeO _{2 in} the electrolyte, the faster the reaction speed, and the efficient the synthesis of GeH _4. Therefore, it is preferably a saturated concentration for a solvent and for water.

In order to improve the conductivity of the electrolytic solution and promote the solubility of GeO ₂ to water, the electrolytic solution preferably contains an ionic substance. As the ionic substance, a conventionally known ionic substance used in electrochemistry can be used, but from the viewpoint of excellent effects as described above, KOH or NaOH is preferred. Among these, KOH aqueous solution is more excellent in electrical conductivity than NaOH aqueous solution, so it is preferably KOH.

The KOH concentration in the electrolyte is preferably 1 to 8 mol / L, and more preferably 2 to 5 mol / L. When the KOH concentration is within the aforementioned range, an electrolyte having a high GeO ₂ concentration is easily obtained, and GeH ₄ can be efficiently produced with high current efficiency. When the KOH concentration does not reach the lower limit of the aforementioned range, the conductivity of the electrolytic solution tends to decrease, a high voltage is required in the production of GeH ₄ , and the solubility of GeO ₂ in water tends to decrease, leading to a reaction. Cases of reduced efficiency. On the other hand, when the KOH concentration exceeds the upper limit of the above range, the electrode or unit material tends to be a material with high corrosion resistance, and the cost of the device may increase.

<Reaction conditions> In this method, the current per unit area (current density) of the cathode at the time of manufacturing GeH ₄ (at the time of the aforementioned energization) is excellent from the viewpoint that the reaction speed is excellent and GeH ₄ can be manufactured at high current efficiency. It is 30 to 500 mA / cm ² , more preferably 50 to 400 mA / cm ² . When the current density is in the aforementioned range, the generation rate or reaction efficiency of GeH ₄ per unit time does not decrease, and the amount of hydrogen generated due to the electrolysis of water can be suppressed to a moderate level.

The reaction temperature for producing GeH ₄ (produced GeH ₄₎ of, based on the reaction rate is excellent, can be manufactured at low cost viewpoint GeH _4, etc., preferably 10 ~ 100 ℃, more preferably 15 ~ 40 ℃. If the reaction temperature is within the aforementioned range, the reaction efficiency does not decrease, and the power consumption for unit heating can be suppressed to a moderate level.

The reaction environment (gas-phase part of the anode chamber and the cathode chamber) when producing GeH ₄ is not particularly limited, but an inert gas environment is preferred, and the inert gas is preferably nitrogen.

In this method, the aforementioned electrolyte in the electrochemical unit may be in a static state, or it may be stirred, or other liquid tanks may be provided and circulated. When other liquid tanks are provided and circulated as described above, the change in the concentration of the reaction solution is relatively small, and the stability of the current efficiency can be expected, and the GeO ₂ concentration on the electrode surface can be kept high, and the reaction speed can be expected to increase. Therefore, the aforementioned electrolyte in the electrochemical cell is preferably circulated.

＜ Manufacturing device of GeH ₄ ＞ This method is not particularly limited if the aforementioned electrochemical cell is used. In addition to this cell, a power source and a measuring means (FT-IR, pressure gauge (PI), etc.) as shown in FIG. 1 can be used. , Accumulators, etc.), nitrogen (N ₂ ) supply path, mass flow controller (MFC), exhaust path and other conventionally known components. Further, a device having the aforementioned circulation flow path and the like (not shown) may be used. [Example]

The following examples specifically illustrate the present invention, but the present invention is not limited to these examples.

[Example 1] As shown in FIG. 1, the following materials were used to produce an electrochemical cell made of vinyl chloride with a separator separating an anode chamber and a cathode chamber.・ Cathode: 0.5cm × 0.5cm × 0.5mm thick Pd plate ・ Anode: 2cm × 2cm × 0.5mm thick Ni plate ・ Separator: NAFION (registered trademark) NRE-212 (manufactured by SIGMA ALDRICH) A 4 mol / L KOH aqueous solution dissolves GeO ₂ at a concentration of 90 g / L. • The amount of electrolyte introduced into the cathode compartment: 100 mL. • The amount of electrolyte introduced into the anode compartment: 100 mL. • Standard electrode: silver-chlorinated on the cathode. Silver electrode

After the gas phase portions of the anode chamber and the cathode chamber in the obtained electrochemical cell were purged with nitrogen (N ₂ ), a battery of Hz-5000 manufactured by Beidou Electric Co., Ltd. was used as a power source, and a current of -100 mA was applied for 37 hours to produce GeH ₄ electrochemically. . The current density at this time was 174 mA / cm ² . In addition, the temperature of the electrochemical cell when the current was applied was not controlled, and as a result, the reaction temperature was 15 to 22 ° C. The total outlet gas (gas containing GeH ₄ and hydrogen) generated by the reaction is measured by using an accumulator to measure the outlet gas of the cathode chamber, and the concentration of GeH ₄ in the total outlet gas is measured using FT-IR. From these measurement results, the amount of GeH ₄ produced was calculated.

The current efficiency was calculated based on the following formula from the amount of GeH ₄ generated and the amount of electricity applied in a specific reaction time of approximately one hour, and the current efficiency was set to the current efficiency of one hour in the reaction time. Similarly, the current efficiency for each reaction time was calculated. The results are shown in Fig. 2. From the results in FIG. 2, no decrease in current efficiency was observed in the 37-hour reaction. Current efficiency (%) = [Equivalent to the amount of GeH ₄ generated (mmol / min) above (C / min) × 60 (min) × 100] / [Total applied amount (C / min) × 60 ( min)]

[Comparative Example 1] A reaction was performed under the same conditions as in Example 1 except that a Cd plate of 1 cm × 1 cm × 0.5 mm in thickness was used as the cathode, and the applied current was changed to -200 mA for 24 hours. The results of the current efficiency calculated in the same manner as in Example 1 are shown in FIG. 3. From the result of FIG. 3, when the reaction time exceeds 12 hours, a decrease in current efficiency is seen.

According to FIG. 2, it can be determined that the current efficiency is about 16% (at a reaction time of about 10 hours when the reaction becomes a substantially stable region) is the current efficiency during normal reactions, and the current efficiency does not decrease even if the reaction exceeds 30 hours. On the other hand, Figure 3 is a mountain-type diagram where the current efficiency of the reaction time = 10 hours becomes the peak. When the reaction time exceeds 10 hours, the current efficiency continues to decrease. Therefore, the cathode (Cd plate) used in Comparative Example 1 cannot withstand long-term reactions. Since the frequency of replacing the cathode or the frequency of maintaining the cathode must be increased, it is considered that the Cd plate does not utilize industrial reactions.

In Comparative Example 1, the current load per unit area of the cathode plate, that is, the current density (200mA / (1cm ² + 1cm ² + (1 × 0.05 × 3)) = 93mA / cm ² ) (100mA / (0.25cm ² + 0.25cm ² + (0.5 × 0.05 × 3)) = 174mA / cm ² ) is small. Compared with Example 1, Comparative Example 1 has a milder reaction time than Example 1, but has a self-reaction time of 10 hours. The left-right starting current efficiency continued to decrease, but in Example 1, the current efficiency did not decrease even after 30 hours or more had passed. In the calculation of the current density, "× 3" is set because one side is hidden by the fixed jig.

Fig. 1 is a schematic diagram of a device used in the embodiment. Fig. 2 is a graph showing the relationship between the reaction time and the current efficiency in the manufacturing method of Example 1. Fig. 3 is a graph showing the relationship between the reaction time and the current efficiency in the manufacturing method of Comparative Example 1.

Claims (6)

A method for electrochemically manufacturing germane is based on an electrochemical cell having a separator, an anode, and a cathode containing palladium, and energizing an electrolyte containing a germanium compound to generate germane at the cathode. The method for producing germane according to claim 1, wherein the aforementioned electrolytic solution is an electrolytic solution containing germanium dioxide and an ionic substance. The method for producing germane according to claim 2, wherein the ionic substance is potassium hydroxide or sodium hydroxide. The method for producing germane according to claim 2, wherein the ionic substance is potassium hydroxide, and the potassium hydroxide concentration in the electrolyte is 1 to 8 mol / L. The method for producing germane according to any one of claims 1 to 4, wherein the aforementioned cathode current density at the time of energization is 30 to 500 mA / cm ² . The method for producing germane according to any one of claims 1 to 4, wherein the aforementioned reaction temperature when producing germane is 10 to 100 ° C.