Process for preparing boron trifluoride gas

Abstract

The invention relates to a process for preparing boron trifluoride gas. The process comprises the following steps of: a, mixing, and generating gas, namely mixing boric acid and 20 percent fuming sulphuric acid under normal pressure, mixing the mixed acid of boric acid and fuming sulphuric acid, and hydrogen fluoride gas in a reaction tower, contacting and reacting in the mass ratio of the mixed acid of boric acid and fuming sulphuric acid to the hydrogen fluoride gas of 9:(0.8-0.9) to generate fluoboric acid, and performing decomposition reaction of fluoboric acid at the presence of the fuming sulphuric acid at the temperature of between 80 and 120 DEG C to generate boron trifluoride gas; b, reacting in an absorption column, namely drying and purifying the boron trifluoride gas and byproduct sulfuric acid which are produced in the gas making process; and c, utilizing the byproduct sulfuric acid, namely adding sodium sulfate into a reaction kettle, adding the byproduct sulfuric acid, and reacting in the mass ratio of sodium sulfate to byproduct sulfuric acid of 1:(4-6), and reacting at normal temperature to generate sodium acid sulfate. The process has the advantages of low reaction temperature, high safety, no waste residue or waste gas, and environment-friendliness, and the waste liquor can be recycled.

Description

technical field [0001] The invention relates to a preparation process of boron trifluoride gas, belonging to the field of chemical industry. Background technique [0002] At present, boron trifluoride is generally produced by adding 20% ​​oleum, boric anhydride, and fluorite in a gas-generating reactor at a mass ratio of 9:1:3 to react with hydrogen fluoride at 130° to produce boron trifluoride gas. , the produced gas is complexed in the above solvent to obtain products; the disadvantage of this reaction process is that the use of fluorite powder as raw material needs to be carried out at a higher temperature, which will cause waste of energy, and high temperature will also aggravate the corrosion and damage of equipment , and the workshop environment is poor during the production process, boron trifluoride gas will contain a large amount of impurities, which will have a certain impact on the quality of downstream products and is intermittent production, and the production c...

AI Technical Summary

Problems solved by technology

[0002] At present, boron trifluoride is generally produced by adding 20% ​​oleum, boric anhydride, and fluorite into a gas-generating reactor with a mass ratio of 9:1:3 to react with hydrogen fluoride at 130° to produce boron trifluoride gas. , the produced gas is complexed in the above solvent to obtain products; the disadvantage of this reaction process is that the use of fluorite powder as raw material needs to be carried out at a higher temperature, which will cause waste of energy, and high temperature will also aggravate the corrosion and damage of equipment , and the workshop environment is poor during the production process, boron trifluoride gas will contain a large amount of impurities, which will have a certain impact on the quality of downstream products and it is intermittent production, and the production capacity of the project has certain restrictions; another process is After adding boric acid to concentrated sulfuric acid, sulfur trioxide is added, and finally hydrogen fluoride is added to generate boron trifluoride gas to complex with the solvent to obtain the product; the shortcoming of this reaction is the use of highly toxic sulfur trioxide, which is difficult to operate and slightly Leakage will cause great pollution to the environment, and the generated waste acid has a high content of sulfur trioxide, which is not easy to use and pollutes the environment