Preparation of 1,1-difluoroethane and fluorating catalyst

Abstract

The invention discloses a method for preparing 1, 1-difluoroethane and a fluorination catalyst using the method. The method is characterized in that in the presence of a chromium-based fluorination catalyst, ethyne and anhydrous hydrofluoric acid are gasified and mixed to undergo gas-phase fluorination reaction so as to generate 1,1- difluoroethane HFC-152a(C2H4F2); the reaction temperature is between 140 and 380 DEG C; the pressure is between 0.3 and 1.8 MPa; under the standard condition, air speed of a reactor is between 300 and 2,200 h<-1>; the mixture ratio of the reaction materials of the anhydrous hydrofluoric acid to the ethyne is 4 to 1-30 to 1; the transformation rate of the ethyne in an outlet of the reactor reaches over 75 percent; and the selectivity of HFC-152a reaches over 90 percent.

Description

technical field

[0001] The present invention relates to a process for the preparation of hydrofluorocarbons (HFCs). Specifically, 1,1-difluoroethane (CH 4 CF 2 ) preparation method. Background technique

[0002] HFC-152a, molecular structure is CH 3 —CHF 2 , the chemical name is 1,1-difluoroethane, the English name is: 1,1-bifluoroethane, the molecular weight is 66, the boiling point is -24.7 ° C, the ozone destruction potential value ODP=0; the global warming coefficient value GWP=0.03, is a An excellent alternative to ODS (Ozone Depleting Substances). Since HFC-152a has very similar physicochemical properties and thermodynamic properties to CFC-12, it is the preferred alternative to CFC-12. The mixed refrigerant HFC-152a / HCFC-22 is one of the main substances used to replace CFC-12, which has a damaging effect on the atmospheric ozone layer in recent years. In my country, as an environmental protection and energy saving working fluid, it is widely used in small refrig...

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