Method for removing impurity of tetrafluoroethylene

Abstract

The invention discloses an impurity removing method in the perfluoroethylene, which comprises the following steps: distilling perfluoroethylene gas with impurity in the degassing tower; controlling certain quantity to rectify in the extracting rectifying tower; adopting oligomer solvent of alcohols, ketones, chloroform and octafluorocyclobutane as extractant; combusting fluoride impurity gas on the top of rectifying tower; adsorbing the component from extracting rectifying tower autoclave; returning the component to rectifying unit directly to obtain the product.

Description

technical field [0001] The invention relates to the field of chemical industry, in particular to a method for removing impurities in tetrafluoroethylene. Background technique [0002] Chlorodifluoromethane (CHClF 2 , hereinafter collectively referred to as F 22 ) needs to pass through following units in the technique that generates tetrafluoroethylene by cracking: cracking unit, acid removal and water removal unit, compression unit, rectification unit, finally obtain the higher tetrafluoroethylene monomer of purity (its process flow chart is shown in accompanying drawing one ), in the cracking unit, F 22 Thermal cracking produces tetrafluoroethylene (C 2 f 4 ) monomer, generate a certain amount of impurities simultaneously such as: carbon monoxide, vinylidene fluoride, trifluoroethylene, difluoromethane, trifluoromethane, and its reaction equation is as follows: [0003] CHClF 2 +H 2 O—→C 2 f 4 +C 2 h 2 f 2 +C 2 HF 3 +CF 2 h 2 +CF 3 H+CHClF 2 +CO+other. ...

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Problems solved by technology

[0008] There are few reports on the recovery of tetrafluoroethylene from the exhaust gas. At present, one method is to use F 113 , methanol, chloroform, ethylene glycol dimethyl ether and other solvents are used as extraction agents, and fluorine-containing gases such as tetrafluoroethylene, difluoromethane, trifluoromethane, vinylidene fluoride, trifluoroethylene and inert gases are separated by extraction and rectification. As carbon monoxide, oxygen and nitrogen are separated, the fluorine-containing gas is returned to the system for rectification to obtain tetrafluoroethylene, but this method has the following obvious disadvantages: 1. Although the method separates the inert gas from the system, the method does not remove the fluorine-containing impurity gas such as Difluoromethane, trifluoromethane, vinylidene fluoride, trifluoroethylene separation system, fluorine-containing impurity gas circulates and accumulates in the system, when accumulated to a certain amount, it will seriously affect the quality of tetrafluoroethylene monomer

2.F 113 During use, it will enter the atmosphere with the exhaust gas, and the F 113 Currently banned due to serious damage to the atmospheric ozone layer, with F 113 is prohibited, the process will no longer be available

3. The solvent has high boiling point, high operating energy consumption, strong corrosiveness, high toxicity, and high requirements on materials. Therefore, in order to ensure the long-term safe operation of the tetrafluoroethylene production system, it is necessary to find a new solvent with high selectivity to tetrafluoroethylene to overcome the problem. Above-mentioned shortcoming, adopting new solvent is the key point of the present invention

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