CN101254942A - Preparation method of high-purity anhydrous indium trichloride - Google Patents

Abstract

The invention relates to a method for preparing high-purity anhydrous indium trichloride, belonging to the technical field of rare metal fine chemicals. Using 99.99-99.999% metal indium and 36% hydrochloric acid as raw materials, using organic solvents n-butanol and n-heptane as dehydrating agents, that is, replacing more stable compounds with less stable complexes, stable crystal water containing three Indium chloride is replaced by a relatively unstable indium trichloride organic solvent complex, and then microwave heating is used to gradually increase the temperature, and there are three steps: normal pressure distillation dehydration, vacuum distillation dehydration, and anhydrous indium trichloride sublimation purification. Finally, white high-purity anhydrous indium trichloride (InCl ₃ ) with a purity of 99.99-99.999% is obtained, and the yield thereof reaches 97%-98%.

Description

Preparation method of high-purity anhydrous indium trichloride

1. Technical field:

The invention relates to a method for preparing high-purity anhydrous indium trichloride, belonging to the technical field of rare metal fine chemicals.

2. Background technology

High-purity anhydrous indium trichloride (InCl ₃ ) is the main raw material for preparing ITO thin films and III-V semiconductor materials. It is one of the important solar cell materials and the basic raw material for the synthesis of organic indium series compounds. It can be used as organic The catalyst of the reaction has a wide range of applications in organic synthesis and electronics industry. my country is a country with large indium resources, and the annual smelting of indium metal can reach 400 tons, ranking first in the world. But the production of InCl ₃ can only produce InCl ₃ 4H ₂ O and InCl ₃ in China at present, and high-purity anhydrous InCl ₃ must be imported, which is expensive. Although there are many methods for preparing anhydrous _InCl3 , such as metal indium direct chlorination method, oxide decomposition chlorination method and hydrate heating dehydration method, organic solvent method, gradual temperature rise chlorination method, etc. The best temperature for direct chlorination with metal indium is 430°C. When it is carefully heated and fed with suitable chlorine gas, misty indium trichloride will be generated; it can also be prepared by reacting carbon tetrachloride with indium oxide. Indium trichloride; Thionyl chloride and indium oxide can also be used together to obtain anhydrous indium trichloride by evaporating the excess reagent. In addition, the gradual temperature rise chlorination method is adopted, and In is used as the raw material, and the temperature is gradually increased to be chlorinated into indium trichloride, and the inert gas is introduced into the protective gas to cool. Wu Shihua synthesized anhydrous indium trichloride by step-up temperature chlorination method. The purification of indium trichloride generally adopts the method of sublimating it one or more times in the flow of chlorine gas or inert gas (N ₂ , Ar, CO ₂ ) or a mixture of the two. Vacuum sublimation can also be used, and at the same time, in order to remove aluminum, iron (III) chloride and other volatile impurities, the reactants can be heated to about 300°C in an inert airflow. The organic solvent method can also be used to purify indium trichloride. Since the H ₂ O in InCl ₃ 4H ₂ O can be replaced by a polar organic solvent with oxygen and nitrogen donors, Zhou Zhihua et al. used n-butanol BuOH as the organic solvent. Solvent, anhydrous indium trichloride was prepared by dehydrating InCl ₃ ·4H ₂ O by an organic solvent method. These preparation methods have their own advantages and disadvantages. Some methods have higher requirements on the purity of raw materials and reagents, stricter temperature control, complex equipment, and lower yields. Some methods are difficult to post-process and cause serious environmental pollution. Although foreign existing literature reports utilize organic solvents such as amine, formamide and kerosene to remove crystal water in crystalline chloride to prepare anhydrous chloride, but also because the processes involved in these reactions are often more complicated, the reaction time is long, The experimental conditions are demanding, the reagents are expensive, the organic reagents are polluted and dangerous, the equipment is bulky, the energy consumption is high, it is not easy to operate, there are few resources, and the cost is high.

3. Contents of the invention

The object of the present invention is to provide a method for preparing high-purity anhydrous indium trichloride. Using 99.99%-99.999% metal indium (In) and 36% hydrochloric acid (HCl) as raw materials, using organic solvents n-butanol and n-heptane as dehydrating agents, that is, replacing more stable compounds with less stable complexes , the stable indium trichloride containing crystalline water was replaced by a less stable indium trichloride organic solvent complex, and then microwave heating was used to gradually increase the temperature, normal pressure distillation dehydration, vacuum distillation dehydration, anhydrous trichloride Three stages of indium sublimation purification are used to finally produce white, high-purity anhydrous indium trichloride (InCl ₃ ) with a purity of 99.99%-99.999%, and a yield of 97%-98%.

The present invention is accomplished by the following steps

(1) Add 99.99-99.999% of raw material indium (In) into hydrochloric acid (HCl) with a concentration of 36% by weight, control the molar ratio of In and HCl to 1:2-4, and heat up to 30-55°C, Continue to stir until the metal indium is completely dissolved to obtain an aqueous solution of InCl ₃ ; evaporate the aqueous solution to obtain a white crystal of indium trichloride tetrahydrate (InCl ₃ 4H ₂ O); add an organic dehydrating agent to the crystal, and control the temperature at 90°C in a microwave oven. At -120°C, carry out atmospheric distillation and dehydration to obtain pasty indium trichloride n-butanol complex or unstable indium trichloride n-butanol and n-heptane mixed complex (InCl ₃ ·mBuOH),

The organic dehydrating agent is n-butanol (BuOH), and the weight ratio (BuOH/H ₂ O) of n-butanol to crystal water contained in indium trichloride tetrahydrate is 35-45, or n-butanol and n-butanol The ratio of heptane is a mixture of 1:1, and the weight ratio of n-butanol+n-heptane mixture to crystal water contained in indium trichloride tetrahydrate is 25-35;

(2) Distill the paste complex (InCl ₃ ·mBuOH) in a microwave oven at a controlled temperature of 130-280°C and a vacuum of 6-10kPa for 5-10min to remove the organic dehydrating agent by vacuum distillation to obtain a white Flake anhydrous indium trichloride (InCl ₃ );

(3) Sublimate and purify anhydrous indium trichloride (InCl ₃ ) in a microwave oven at a controlled temperature of 300-400°C for 5-10 minutes to obtain white fluffy needle-shaped high-purity anhydrous indium trichloride (InCl 3 ) with metallic luster ( InCl ₃ ) crystal product.

Compared with known technology, the present invention has advantages and positive effects

(1) High-purity anhydrous indium trichloride is prepared by microwave heating step by step method, which has short time, high yield, less pollution and good product quality. The method overcomes the disadvantages of high-temperature preparation of indium trichloride in conventional methods, such as complex process, high power consumption, long time, high cost, and long process flow. The problem that the solvent cannot be reused and the high-temperature product deteriorates in the organic solvent drying method is solved.

(2) The selected organic dehydrating agent makes the reactant InCl ₃ 4H ₂ O more soluble in it; the solvent can effectively separate water and is easy to recover; the solvent has better chemical stability to InCl ₃ , that is, the side reaction The least; the reaction product does not interact with the solvent; the solvent and the product are easy to separate; the solvent has low toxicity, no pollution and is cheap.

4. Specific implementation

Embodiment 1: get 99.99% pure metallic indium (In) 11.48g and add the hydrochloric acid (HCl) 50ml that is 36% by weight percent concentration, be warming up to 45 ℃, keep stirring until metallic indium dissolves completely and obtain InCl ₃ aqueous solution, the aqueous solution Evaporated to get tetrahydrate indium trichloride (InCl ₃ 4H ₂ O) white crystals; 245ml of n-butanol (BuOH) was added to the crystals, and the ratio (BuOH/H ₂ O) of n-butanol to water of crystallization was 35, At a _temperature of 100°C, carry out atmospheric distillation and dehydration to obtain a pasty product of indium trichloride n-butanol complex (InCl ₃ ·mBuOH); mBuOH) for 10 min under reduced pressure, with a vacuum of 8 kPa, to obtain anhydrous indium trichloride (InCl ₃ ); at this time, the temperature was raised to 350° C. for sublimation and purification of anhydrous indium trichloride (InCl ₃ ) for 10 min, to obtain White fluffy needle-like high-purity anhydrous indium trichloride (InCl ₃ ) crystal product with metallic luster. Its purity reaches 99.9958%, and its yield reaches 97%.

Embodiment 2: get 99.99% pure metallic indium (In) 11.48g, add the hydrochloric acid (HCl) 50ml that is 36% concentration by weight, heat up to 45 ℃, continue to stir until metallic indium dissolves completely, obtain InCl ₃ aqueous solution, put The aqueous solution was evaporated to obtain white crystals of indium trichloride tetrahydrate (InCl ₃ 4H ₂ O); a mixture of 105ml of n-butanol and 105ml of n-heptane was added to the crystals, and at a temperature of 95°C, under normal pressure Distillation and dehydration to obtain a pasty unstable mixed complex of indium trichloride, n-butanol and n-heptane (InCl ₃ ·mBuOH); the pasty complex (InCl ₃ ·mBuOH) was distilled under reduced pressure at a temperature of 150°C 8min, the vacuum degree is 8kPa, and white flake anhydrous indium trichloride (InCl ₃ ) is obtained; anhydrous indium trichloride (InCl ₃ ) is sublimated and purified at a temperature of 350°C for 10min, and white fluffy needles with metal Glossy high-purity anhydrous indium trichloride (InCl ₃ ) crystal product. Its purity reaches 99.9974%, and its yield reaches 98%.

Claims (2)

1. A method for preparing high-purity anhydrous indium trichloride, characterized in that: the present invention is completed according to the following steps, (1) Add 99.99-99.999% of the raw material indium to hydrochloric acid with a concentration of 36% by weight, control the molar ratio of In and HCl to 1:2-4, raise the temperature to 30-55°C, and keep stirring until the indium is completely Dissolve to obtain InCl ₃ aqueous solution; evaporate the aqueous solution to obtain white crystals of indium trichloride tetrahydrate; add an organic dehydrating agent to the crystals, and conduct atmospheric distillation and dehydration in a microwave oven at a controlled temperature of 90-120°C to obtain pasty indium trichloride Indium chloride n-butanol complexes or unstable indium trichloride n-butanol and n-heptane mixed complexes; (2) Distill the pasty complex in a microwave oven at a controlled temperature of 130-280°C and a vacuum of 6-10kPa for 5-10 minutes to remove the organic dehydrating agent by vacuum distillation to obtain white flaky anhydrous trichloride Indium; (3) Sublimation and purification of anhydrous indium trichloride in a microwave oven at a controlled temperature of 300-400° C. for 5-10 minutes to obtain a white fluffy needle-shaped high-purity anhydrous indium trichloride crystal product with metallic luster. 2. The method for preparing high-purity anhydrous indium trichloride according to claim 1, characterized in that: the organic dehydrating agent is n-butanol or the ratio of n-butanol to n-heptane is 1:1 Mixing agent, the weight ratio of n-butanol to indium trichloride tetrahydrate containing crystal water is 35-45, the weight ratio of n-butanol and n-heptane mixture to crystal water contained in tetrahydrate indium trichloride for 25-35.