Method for preparing ultrapure fluoromethane

A technology of monofluoromethane and fluoromethane, which is applied in the field of gas purification, can solve problems such as difficult separation, and achieve the effects of no secondary pollution, environmental friendliness, and high adsorption rate

Inactive Publication Date: 2014-07-09
SINOCHEM LANTIAN +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0009] However, since this reaction is an equilibrium reaction as shown in the above chemical equation (2), the problem of this method is the need to increase the catalytic activity, and the problem that it is difficult to separate due to the formation of an azeotropic mixture of HFC-41 and hydrogen chloride close in boiling point

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0024] First put a certain amount of 4A molecular sieve into the muffle furnace with a tray, heat to 300°C for activation, and keep the activation time for 3 hours before taking it out. Weigh 300g of the activated 4A molecular sieve and place it in a 1L stainless steel cylinder, seal it, vacuumize it, then add 400g of a fluoromethane crude product (impurity content: methane 10ppm, ethylene 3ppm, ethane 1ppm, propylene 2ppm, Propane 103ppm), start to adsorb at room temperature until the adsorption equilibrium. The results after adsorption equilibrium are shown in Table 1.

Embodiment 2

[0026] First put a certain amount of 5A molecular sieve into the muffle furnace with a tray, heat it to 300°C for activation, and keep the activation time for 3 hours before taking it out. Weigh 300g of the activated 5A molecular sieve and place it in a 1L stainless steel cylinder, seal it, vacuumize it, then add 400g of a fluoromethane crude product (the content of impurities is the same as in Example 1) to the 1L steel cylinder, and start adsorption at room temperature until the adsorption equilibrium . The results after adsorption equilibrium are shown in Table 1.

Embodiment 3

[0028] First put a certain amount of activated carbon into the oven with a tray, heat to 180°C for activation, keep the activation time for 3 hours and then take it out. Take by weighing 300g of activated carbon and place it in a 1L stainless steel cylinder, seal, vacuumize, then add 400g of a fluoromethane crude product (impurity content is the same as in Example 1) in the 1L steel cylinder, and start adsorption at room temperature until adsorption equilibrium. The results after adsorption equilibrium are shown in Table 1.

[0029] Table 1

[0030] Example

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PUM

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Abstract

The invention provides a method for preparing ultrapure fluoromethane through an adsorption process. Impurities in crude fluoromethane are removed by adopting A-type molecular sieve and / or active carbon with the particle size of 1.5-3.0mm, and the A-type molecular sieve and active carbon are activated before use. Highly pure fluoromethane with the purity of above 99.99 even 99.9999% can be obtained through the preparation method, and the prepared ultrapure fluoromethane can be used in the semiconductor / electron industry as an etching gas.

Description

technical field [0001] The invention belongs to the technical field of gas purification, and relates to a method for preparing ultra-high-purity monofluoromethane. Background technique [0002] Monofluoromethane, the chemical formula is CH 3 F, code-named R41 or HFC-41, is a non-toxic, colorless, odorless, flammable liquefied gas stored in steel cylinders. Methyl fluoride is used in the manufacturing process of semiconductors and electronic products. Under the radio frequency field, fluoromethane will dissociate fluorine ions, which can selectively etch the thin film of silicon compound, that is, reactive-ion etching. The purity requirements of monofluoromethane etching gas are very strict, and often need to be greater than 99.99%, or even 99.999%. [0003] There are two main methods for the preparation of fluoromethane, using methyl alcohol and methyl chloride as raw materials respectively. [0004] Japanese Patent No. 4-7330 discloses a method for preparing HFC-41, wher...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07C19/08C07C17/389
Inventor 李盛姬柳彩波刘武灿
Owner SINOCHEM LANTIAN
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