Methods for purifying and stabilizing hydrofluoroolefins and hydrochlorofluoroolefins

Purification of Commercial 1234yf by Contact with Activated Alumina

[0050]In this example, a commercial sample of 1234yf, containing 150 ppm of trifluoroacetic acid and 200 ppm of HF, as quantitatively determined by ion chromatography (IC), was fed over 85 g of Engelhard 4028 alumina, which had been previously activated by heating at 150° C. for approximately 4 hours. The dry activated alumina had a surface area of 223 m2 / g and a pore volume of 0.49 g / cc, at 22° C., at a rate of 20 cc / m. The contact time was about 5.3 minutes. Analysis of the purified 1234yf found less than 5 ppm of trifluoroacetic acid and less than 5 ppm of HF by IC.

Accelerated Aging Test of Acid-Free 1234yf

[0051]The acid-free 1234yf obtained from Example 1 was placed in an aerosol bottle. The bottle was capped in the presence of air and aged at 50° C. for 18 hours, in the presence of a metal coupon selected from Cu, 304SS, and Al. Analysis of the 1234yf by IC showed less than 5 ppm trifluoroacetic acid and HF. Visual inspection of the metal coupon found no evidence of corrosion or discolorations.

Stabilization of Commercial 1234yf by the Addition of Inhibitors

[0052]Impure 1234yf (20 grams) containing trifluoroacetic acid (150 ppm) and HF (200 ppm) was placed in a 50 cc aerosol glass bottle in combination with 500 ppm of α-methyl styrene. The same procedure was repeated with an additional five bottles, each containing 500 ppm of one of the following inhibitors: 1,2-epoxy butane, α-pinene oxide, β-pinene oxide, hexadecene oxide, and α-glycidyl isopropyl ether. After aging at 50° C. for 18 hours, IC analysis showed no increase in the level of trifluoroacetic acid or HF in any of the samples.