Purification of hydrofluorocarbons

Details Purification of hydrofluorocarbons Purification of hydrofluorocarbons

1998-03-31

2002-12-03

Manoharan, Virginia (Department: 1764)

Distillation: processes, separatory

Plural distillations performed on same material

One a distillation under positive pressure or vacuum

C203S075000, C203S077000, C203S078000, C203S080000, C203S067000, C203SDIG001, C570S178000

Reexamination Certificate

active

06488817

ABSTRACT:

FIELD OF INVENTION
The present invention relates broadly to the purification of hydrofluorocarbons. More specifically, the present invention relates to the separation of an azeotrope of dichloromethane (HFC-32) and dichlorodifluoromethane (CFC-12).
BACKGROUND OF THE INVENTION
Difluoromethane (HFC-32) is a hydrofluorocarbon developed to replace ozone-depleting hydrochlorofluorocarbons (HCFCs) or chlorofluorocarbons (CFCs) refrigerants/refrigerant blends. During the production of HFC-32, certain by-products are formed, including CFC-12, which is of particular interest herein. It has been found that CFC-12 and HFC-32 form a low-boiling azeotrope in the distillation of HFC-32.
Such an azeotropic cannot be separated using conventional distillation techniques. Furthermore, alternative methods of separating CFC-12 from HFC-32 such as extraction, extractive distillation, or absorption introduce higher costs and additional components to the purification process.
Although further recovery of HFC-32 tends to be difficult, it is nevertheless necessary to maintain high yields. For example, if no additional recovery of HFC-32 is performed on an azeotropic distillate containing about 9.2 wt % CFC-12 (as would be obtained through economical, high pressure distillation), then an HFC-32 yield loss of at least 10% can be expected. In other words, without further recovery, the HFC-32 yield would be less than 90%.
Therefore, a need exists for a process which recovers HFC-32 in high yield from the CFC-12/HFC-32 azeotropic distillate, but which does not involve costly and complex distillation techniques and apparatus. The present invention fulfills this need among others.


REFERENCES:
patent: 5346595 (1994-09-01), Clemmer
patent: 5470442 (1995-11-01), Mahler et al.
patent: 5523015 (1996-06-01), Tsuda et al.
patent: 5707497 (1998-01-01), Galland et al.
patent: 5785822 (1998-07-01), Cerri et al.

Affiliated with

Also associated with

Rating

Purification of hydrofluorocarbons does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Purification of hydrofluorocarbons, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Purification of hydrofluorocarbons will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-2974862