| 摘要 |
A process for the purification of difluoromethane (F32) contg. traces of chloro-fluoromethane (F31), by passing a gaseous current of the F32 through a 13X molecular sieve at a temp. of at least 60 degrees C. F32 is a possible substitute for CFC's, in partic. chloro-pentafluoroethane (F115) which is active towards ozone and has a marked `greenhouse' effect. In the prepn. of F32, F31 is generally formed as an intermediate : the latter cpd. is toxic and a potential carcinogen, and it is therefore necessary to reduce its content to a ppm level. This is achieved by use of a molecular sieve 13X which is an X/Y synthetic zeolite of crystalline structure having pores of effective dia. 10 Angstrom, of surface area 800-1000 m<2>/g in the Na form corresp. to the formula Na86Ä(AlO2)86(SiO2)106Ü276H2O. |
