SU621664A1 - Method of purifying 1,1,2-trifluorotrichlorethane - Google Patents

Description

This invention relates to the purification of 1 / 1,2-trifluorotrichloroethane (freon 113). Freon-113 is widely used as a solvent and feedstock for the production of fluorine-containing monomer, trifluorochloroethylene. A known method of purification of freon113, obtained by liquid-phase hydrofluorination of polychloroethanes in the presence of a catalyst — surfactant chloride, from acidic impurities — fluoride and hydrogen chloride, is done by treating organic products with 4% (by weight) aqueous solution of caustic soda in a countercurrent packed column with the subsequent sedimentation and separation of the spent alkaline solution, the repeated purification of organic products, a mixture of solid caustic soda with sodium hyposulphite and then activated carbon, followed by rectif katsiey fl}. The disadvantages of this method are: significant losses of freon with spent alkali during purification of organic products, due to the formation of insoluble compounds, absorbing freon, a large amount of polluted effluent due to frequent and prolonged washing of the column with hot water, low efficiency of purifying freon from antimony compounds. The purpose of the invention is to increase the cleaning efficiency, reduce the loss of the target product and reduce the amount of wastewater. This goal is achieved by the described method of purification of 1,1,2-trifluorotrichloroethane, concluded that organic products of hydrofluorination of polychloroethanes are treated with a solution of caustic potash, carbonate or potassium bicarbonate with a concentration of 2-130 g / l. It is preferable to conduct the process with vigorous stirring. This makes it possible to reduce the loss of freon with spent alkali to the level of physical solubility, to increase the efficiency of purification of freon from antimony compounds, to virtually eliminate the formation of precipitation, which leads to a sharp decrease in the number of leaching equipment with hot water and a significant decrease in wastewater. Example. In a polyethylene device with a capacity of 1 l, equipped with

A metal diffuser and a propeller stirrer were charged with 500 g of acidic freonates and 312.5 g of a 5% aqueous solution of caustic potassium (caustic potassium content of 46.5 g / l), the mixture was stirred at a temperature of 10 minutes with intensive mixing, settled into long funnel for 1 h, the layers are separated and analyzed.

The results of the analyzes when using the recommended alkaline agents are presented in table. one.

Comparison of the effectiveness of the proposed method of purification of 1,1,2-trifluorouyuretan compared with limestone purification method is presented in

tab. 2, illustrating the higher efficiency of the proposed method, cleaning.

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Formula for Inventing Wastewater, as alkaline

1. Purification method; lf1 3-trifluoro-bicarbonate or potassium carbonate with coitrichloroethane, obtained by a hydrofluorination of 2-130 g / l. by the treatment of polychloroethanes in the presence of 2. Method pop. 1, distinguished; in the course of the catalyst, antimony chloride, and with the fact that the treatment with water

from catalyst impurities and. impurities with a solution of an alkaline agent

sour character, by means of papi-pi, intensive mixing. Trays with an aqueous solution of an alkaline agent. Sources of information taken

the one characterized in that during examination: that, in order to reduce the losses of cellenbrg. Technological regulation of the product, to improve the efficiency of production of freon-113, 1969,

cleaning and sozgodeni quantities. A-161U, p. 5-15.

agents use potassium hydroxide,