JPS623019A - Production of titanium tetrafluoride - Google Patents

Abstract

PURPOSE:To produce high-purity titanium tetrafluoride, by reacting nitrogen trifluoride with metallic titanium to form a titanium tetrafluoride gas and cooling and solidifying the gas. CONSTITUTION:Nitrogen trifluoride (NF3) is brought into contact with metallic titanium such as sponge titanium, etc. at >=200 deg.C to form titanium tetrafluoride (TiF4). TiF4 is immediately vaporized since its sublimation temperature is an extremely low temperature of 240 deg.C, the metallic titanium is continuously reacted with NF3 because the new surface of the metallic titanium is successively exposed, to evolve efficiently a TiF4 gas. This gas is cooled and solidified to produce extremely high-purity solid TiF4.

Description

Detailed Description of the Invention The present invention produces gaseous titanium tetrafluoride by bringing nitrogen trifluoride and metallic titanium into contact and reacting, and by cooling and solidifying the titanium tetrafluoride gas, This invention relates to a method for obtaining highly pure titanium tetrafluoride.

Titanium tetrafluoride is a useful compound used as a mild fluorinating agent and also for surface treatment by chemical vapor deposition.

Conventionally, methods for producing titanium tetrafluoride include (1)
A method of reacting titanium tetrachloride with anhydrous hydrogen fluoride.

(2) A method of reacting metallic titanium and fluorine at a temperature of 150°C or higher (J, Am, Chem, Soc, 7
6 r2'177 (1954)) are known.

However, in method (1), the raw material titanium tetrafluoride is mixed into the titanium tetrafluoride produced, and further purification steps such as distillation are required to obtain titanium tetrafluoride with good purity. Method (2) has drawbacks such as disadvantages in terms of operational safety and reaction controllability because it handles fluorine gas, which has strong reactivity.

The present invention takes the above circumstances into consideration and aims to provide a simple, safe, and highly purified method for producing titanium tetrafluoride.

In order to achieve the above object, as a result of repeated studies, the present inventors brought nitrogen trifluoride into contact with metallic titanium at a temperature of 200°C or higher, and by collecting the generated titanium tetrafluoride gas, The present invention was completed by discovering that highly pure titanium tetrafluoride can be produced extremely efficiently.

That is, the gist of the present invention is to cool and collect titanium tetrafluoride gas produced by bringing nitrogen trifluoride and metallic titanium into contact at a temperature of 200°C or higher, preferably at a temperature of 250°C to 400°C, to achieve a purity of 99%. A method for producing titanium tetrafluoride characterized by obtaining titanium tetrafluoride having a molecular weight of .94 or higher.

Titanium fluoride generally includes titanium trifluoride (blue solid, sublimation temperature 950°C) and titanium tetrafluoride (white solid,
The sublimation temperature (284°C) is known. Since the method of the present invention produces titanium tetrafluoride with a low sublimation temperature,
The titanium tetrafluoride produced on the titanium surface during the reaction immediately vaporizes, constantly exposing new titanium surface, allowing for effective use of titanium, and the efficiency of the reaction is very high.

The reaction in the method of the present invention is according to the following formula.

NFs + 3/4Ti→1/2N2+ 3/4TiF
4(1) In addition to titanium tetrafluoride gas, the reaction product gas may also contain nitrogen gas (bp, -196°C) and, depending on the conditions, a trace amount of nitrogen trifluoride gas (bp -129°C). It will be done. By cooling these mixed gases, only titanium tetrafluoride can be easily collected as solid titanium tetrafluoride. The collection method may be a commonly known method and is not particularly limited.

The metallic titanium used as a raw material may be easily available, such as ordinary spontium, zotitanium, etc., and its shape may be granular,
It is not particularly limited as long as it is rod-shaped, wire-shaped, etc., and has good operability.
According to 51), Su? titanium (e.g. TS-10
The purity of titanium metal in 5M) is 99.6% or more, and metal elements such as 0.10% or less iron, 0.01% or less manganese, and 0.06% or less magnesium are included as impurities.

When these impurity metals are fluorinated, iron difluoride (melting point: 1000°C or higher), iron trifluoride (sublimation: 1000°C), manganese difluoride (melting point: 856°C).

Magnesium difluoride (melting point: 1263°C) and other substances are generated, but since they are all compounds with high melting points, these impurity metal components may be mixed into the titanium tetrafluoride gas in the gas phase. Nitrogen trifluoride used in the present invention may be used as is for the reaction, or may be diluted with an inert gas such as nitrogen or helium. The reaction temperature is 200°C or higher.

Particularly preferred is 250°C to 400°C. At a temperature of 200° C. or lower, the vapor pressure of the titanium tetrafluoride produced is low and the surface of the titanium is covered with solid titanium tetrafluoride, inhibiting the progress of the reaction, which is not preferable from the point of view of effective use of titanium. 4
A temperature of 00° C. or higher is not advantageous in terms of the material of the reactor and reaction control, since local overheating occurs inside the reactor due to reaction heat. However, even in such a case, such local overheating can be prevented by diluting with an inert gas such as nitrogen or helium to reduce the nitrogen trifluoride concentration. The reaction method is not particularly limited, but the usual flow type is simple in equipment and easy to operate.

Example EXAMPLES The present invention will be specifically explained below with reference to Examples.

[Example 1] A 4 to 8 mesh strip was placed in a nickel reaction tube with an inner diameter of 20 wφ. Titanium (Japanese Industrial Standards TS-105M).

The reaction tube was filled with 60 l of titanium (purity of 99.6% or more) and maintained at 300° C. by an external heater.

Nitrogen trifluoride gas was introduced at a flow rate of 1.26/hr,
The reaction was carried out continuously for 0 hours.

The produced gas was passed through a cylindrical container having an internal volume of 300+y+l and equipped with an internal cooler (water cooling) to solidify and collect metal fluorides. When the gas at the outlet of the collection container was analyzed by GC, no unreacted nitrogen trifluoride was detected.

The collected metal fluoride is white powdered titanium tetrafluoride (purity 9
9.9% or more), and as a result of elemental analysis, metal impurities such as iron, manganese, and magnesium were not detected. The amount collected was 49.6. F, which corresponds to a yield of 98.8% based on nitrogen trifluoride.

[Example 2] A reaction was carried out using the same apparatus as in Example 1 and the same titanium filling amount. At a reaction temperature of 330°C, nitrogen trifluoride IQ
A mixed gas having a composition of 90 vol % nitrogen and 90 voi % nitrogen was introduced at a flow rate of 241/hr, and the reaction was carried out continuously for 6 hours.

The generated gas was passed through a collection container similar to that in Example 1, and titanium tetrafluoride was solidified and collected. No unreacted nitrogen trifluoride was detected in the gas at the outlet of the collection container. The amount of titanium tetrafluoride (purity 9' 9.94 or higher) collected is 59.2
．． 9, which corresponds to a yield of 99.5% based on nitrogen trifluoride.

Effects of the Invention As described above, the present invention provides a method for easily and safely producing highly efficient titanium tetrafluoride with high purity by bringing nitrogen trifluoride into contact with metallic titanium. It is something.

Claims (1)

[Claims] A method for producing titanium tetrafluoride, which comprises bringing nitrogen trifluoride into contact with metallic titanium to produce gaseous titanium tetrafluoride.