KR101991499B1 - Method for preparing calcium hydride - Google Patents

Abstract

The present invention relates to a method for preparing high-purity calcium hydride at low costs, which comprises the steps of: inputting a calcium metal in a crucible, and placing the calcium metal in a heating region of a furnace; converting the calcium metal into calcium hydride; and collecting the converted calcium hydride.

Description

[0001] METHOD FOR PREPARING CALCIUM HYDRIDE [0002]

The present invention relates to a novel process for producing calcium hydride, and more particularly, to a process for producing calcium hydride of high purity at a low cost by promoting a reaction between calcium metal and hydrogen gas.

Calcium hydride is a compound represented by the formula CaH ₂ , which is an alkaline earth metal. The structure of calcium hydride is a crystal having an orthorhombic structure which is similar to a salt and is white in pure form. However, it is difficult to find white hydrides of orthorhombic structure, usually gray matter.

Calcium hydrides are generally used for:

Desiccant

Calcium hydride is a mild desiccant. Because of these properties, they can be used more safely than reactive materials such as sodium-potassium alloys or sodium metal. The reaction is as follows:

[Reaction Scheme 1]

CaH ₂ + 2H ₂ O - > Ca (OH) ₂ + 2H ₂

The hydrolysis products of this reaction, hydrogen (gas) and Ca (OH) ₂ (solution), can be separated by filtration, distillation or decanting.

Calcium hydride is an effective drying agent for many basic solvents such as amines and pyridines. Sometimes, reactive drying agents are used to dry the solvent before use.

Hydrogen production Hydrogen production)

In the 1940s, calcium hydride was used for many years as a hydrogen source with the trade name "Hydrolith". It is also being used to produce pure hydrogen in laboratories for various experiments such as fuel cells and batteries. In addition, calcium hydride has been widely used for decades as a safe and convenient means of inflating climate balloons. It is also used to produce small quantities of pure hydrogen in the laboratory for laboratory use. The water content of combustible diesel is calculated by hydrogen with CaH ₂ treatment.

Reducing agent

Calcium hydride can be used for powder metallurgy. Zirconium, niobium, uranium, chromium, titanium, vanadium, and tantalum oxide may be heated to 600 to 1000 ° C. together with calcium hydride to reduce the metal oxides to produce the metals in powder form. The following reaction describes the reaction that calcium hydride acts as a reducing agent of titanium oxide.

[Reaction Scheme 2]

TiO ₂ + CaH _{2 -} > CaO + H ₂ + Ti

The following describes the known methods for making calcium hydride.

Most prior art documents describe a method for producing calcium hydride by introducing and reacting calcium into a hydrogen gas at a temperature range of 300 to 400 DEG C, but does not provide specific information on the treatment process. Although a method for producing calcium hydride is described in Bulanov et al., Synthesis of High-Purity Calcium Hydride, Russian Journal of Applied Chemistry, Vol. 77, No. 6, 2004, pp 875-877, Calcium hydride is prepared by shaving, filling the reactor with high purity hydrogen gas at a temperature of 300 to 450 ° C at a pressure of 5 atm, and slowly reducing the pressure to 0.05 to 1 atm. However, this method can not use hydrogen gas of the general grade, the reaction process is not safe, and there is a problem that the complicated equipment must be used for the pressurizing condition.

Two known methods for preparing other calcium hydrides are as follows.

The first method involves reacting calcium chloride with hydrogen and sodium metal as shown in Scheme 3 below.

[Reaction Scheme 3]

CaCl ₂ + H ₂ + ₂ Na → CaH ₂ + 2 NaCl

In this reaction, calcium chloride (CaCl ₂ ) and hydrogen (H) form calcium hydride (CaH ₂ ), and sodium (Na) atom bonds with chlorine (Cl) to form sodium chloride.

The second method is a method of producing calcium hydride by reducing calcium oxide (CaO) with magnesium (Mg) as shown in the following reaction formula (4). This method is carried out in the presence of hydrogen and further produces magnesium oxide (MgO).

[Reaction Scheme 4]

CaO + Mg + H _{2 -} > CaH ₂ + MgO

However, the above-described known methods have a problem in that they are expensive and environmental pollution occurs.

It is an object of the present invention to provide a method for producing high purity calcium hydride using a simple process and equipment.

A) placing a calcium metal in a crucible and placing it in a heating zone of the furnace; b) heating the furnace at a temperature of 550 to 750 占 폚 in a hydrogen gas atmosphere for 1 hour to 10 hours to convert the calcium metal to calcium hydride; And c) collecting the converted calcium hydride.

Preferably, the calcium metal may be in the form of granules or pieces.

Also preferably, the calcium hydride has the same shape as the calcium metal.

Also, preferably, in the step b), the hydrogen gas atmosphere may be formed by supplying hydrogen gas at a flow rate of 2 to 4 l / min at normal pressure.

Also preferably, in step a), the calcium metal may be positioned within the crucible at a thickness of 30 mm to 50 mm.

Since the manufacturing method according to the present invention does not use high-pressure hydrogen gas, there is no need to apply a high pressure, and high-safety equipment is not necessary, and safety is excellent. In addition, the present invention can use a low-cost apparatus such as a general furnace, which can increase the production scale, and the production yield can be excellent, so that the production cost of calcium hydride can be remarkably reduced.

Further, the calcium hydride prepared by the method of the present invention can be used to produce titanium metal or an alloy powder of a metal other than titanium.

Figure 1 is a photograph of calcium metal granules used in the method of the present invention.
Figure 2 is a photograph of calcium hydride granules prepared according to the present invention.
3 shows the XRD measurement results of the calcium hydride powder prepared according to the present invention.

Unless defined otherwise, all technical terms used in the present invention have the following definitions and are consistent with the meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. In addition, preferred methods or samples are described in this specification, but similar or equivalent ones are also included in the scope of the present invention.

The term "about" is used herein to refer to a reference amount, level, value, number, frequency, percentage, dimension, size, quantity, weight or length of 30, 25, 20, 15, 10, 9, 8, 7, Level, value, number, frequency, percent, dimension, size, quantity, weight or length of a variable, such as 4, 3, 2 or 1%.

Throughout this specification, the words "comprises" and "comprising ", unless the context requires otherwise, include the steps or components, or groups of steps or elements, Steps, or groups of elements are not excluded.

The process for preparing calcium hydride of the present invention comprises the following steps:

a) placing a crucible in a heating zone of a furnace with a calcium metal in the crucible (S11);

b) heating the furnace at a temperature of 550 to 750 占 폚 in a hydrogen gas atmosphere for 1 hour to 10 hours to convert the calcium metal to calcium hydride (S12); And

c) collecting the converted calcium hydride (S13).

Each step will be described in detail below.

First, calcium metal as a raw material is placed in the crucible and placed in the heating zone of the furnace (11). The calcium metal may be calcium metal shavings or calcium metal granules. The furnace is not particularly limited, but a tubular furnace can be used. The crucible may preferably have a semicircular cross section. Preferably, the crucible may be made of high-temperature stainless steel such as SUS310S (Japanese standard). The furnace is not particularly limited and any type of furnace can be used, but a furnace having gas hermeticity capable of withstanding a high temperature of 550 DEG C or higher and used in a reduction reaction process can be used. Particularly a furnace capable of reaction under the aforementioned gas conditions such as hydrogen gas. Preferably a tube furnace.

The calcium metal may be in the form of a granule or shavings having a purity of 99.5%, and is not particularly limited in shape. Preferably, the calcium metal may be in the form of granules and the granule size may be from 0.02 mm to 2 mm. If the particle size is greater than 2 mm, the reaction rate with hydrogen is lowered. If the particle size is smaller than 0.02 mm, Is required and the economical efficiency is low.

When depositing the calcium metal in the crucible, it is preferred that the calcium metal is deposited in the crucible at a thickness of 30 mm to 50 mm. The thickness of the calcium metal can be controlled according to the size of the crucible and the uniform zone range of the furnace temperature.

Next, the furnace is heated to a temperature of 550 to 750 占 폚 under a hydrogen gas atmosphere and maintained for 1 hour to 10 hours to convert the calcium metal to calcium hydride (S12). Preferably 600 to 700 < 0 > C. Further, it is preferably maintained for 1 to 4 hours, more preferably 1 to 3 hours. More preferably at a heating rate of 1 to 20 占 폚 / min to 600 占 폚 and maintained for 2 hours. In this step, the calcium metal may be converted into calcium hydride by heat treatment in a furnace in a hydrogen gas atmosphere. Since the hydrogen gas can use hydrogen gas of a general grade and is used at normal pressure without a separate pressurization process during heat treatment, it is difficult to enlarge the facility and it is not necessary to use an unsecured pressurized gas.

The hydrogen gas atmosphere can be formed by flowing hydrogen gas at a flow rate of 2 to 4 l / min into the furnace. Preferably, the supply flow rate of the hydrogen gas may be 3 l / min. The supply flow rate of the hydrogen gas can be adjusted according to the size of the furnace. As the hydrogen gas flows into the furnace, atmospheric pressure is formed in the furnace. The heating may be performed at a heating rate of 1 to 20 ° C / min, more preferably at 10 ° C / min. At this stage, hydrogen is reduced in the calcium metal to form calcium hydride.

When the heating is completed, the furnace is cooled to room temperature and the crucible is taken out of the furnace. The cooling is performed without using any special cooling means, and the calcium hydride is collected in the crucible upon completion of cooling (S13).

The finally prepared calcium hydride has the same shape as the raw calcium metal. When the calcium metal is a granule, the calcium hydride has a granular form, and when the calcium metal is in a granular form, the calcium hydride has a sliced form. When the finally prepared calcium hydride is granular, the size of the granules may be 0.02 to 2 mm.

The calcium hydride thus prepared may be molded into powder or any shape according to the intended use.

Hereinafter, the present invention will be described in detail by way of examples, but the scope of the present invention is not limited by these examples.

Example 1

100 g of calcium metal granules (purity: 99.5%, Xinkang Advanced Materials Co., ltd, China) having a particle size distribution of 0.02 to 2 mm in particle size was placed in a crucible made of SUS310S stainless steel, Outer diameter 100 mm, length 1,000 mm). The furnace was heated to 600 ° C at a rate of 10 ° C / min and maintained for 2 hours while supplying hydrogen gas of normal grade without pressurization to the furnace at a flow rate of 3 l / min. Thereafter, the furnace was cooled to room temperature, and the crucible was taken out from the furnace to obtain 100 g of granular calcium hydride.

Figure 1 is a photograph of calcium metal granules used in the method of the present invention, and Figure 2 is a photograph of calcium hydride granules prepared in accordance with the present invention. Referring to FIG. 1, the raw calcium metal granules are dark gray, whereas the calcium hydride granules of FIG. 2 are light gray. Comparing FIG. 1 and FIG. 2, it can be seen that the volume of calcium hydride granule and calcium hydride granule is almost unchanged, and the weight is also the same.

An X-ray diffraction analyzer (Rigaku, DMAX 2200) was used to confirm that the material prepared according to Example 1 was calcium hydride granules. FIG. 3 shows the XRD measurement results of the calcium hydride powder prepared according to the present invention, and Table 1 summarizes the results. As a result of XRD measurement, it can be confirmed that 99% of the final product is calcium hydride.

sign Compound name The Remarks # Calcium hydride CaH ₂ CaH ₂ 99% ¤  Calcium oxide CaO  CaO 1%

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the same is by way of illustration and example only and is not to be construed as limiting the scope of the present invention. Accordingly, the actual scope of the present invention will be defined by the appended claims and their equivalents.

Claims (6)

a) placing a granular calcium metal having a particle size of 0.02 mm to 2 mm in a crucible and placing it in a heating zone of the furnace;
b) heating the furnace at a temperature of 550 to 750 占 폚 in a hydrogen gas atmosphere at normal pressure for 1 hour to 10 hours to convert the calcium metal to calcium hydride; And
c) collecting the converted calcium hydride,
In the step b), the hydrogen gas atmosphere is formed by supplying hydrogen gas at a flow rate of 2 to 4 l / min at normal pressure,
Wherein the converted calcium hydride has a particle size of 0.02 mm to 2 mm. The method of claim 1, wherein the calcium hydride has the same shape as the calcium metal. The method of claim 1, wherein in step a), the calcium metal is positioned within the crucible at a thickness of 30 mm to 50 mm. delete delete delete

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