| 摘要 |
1,156,560. Separating hydrogen chloride and hydrogen fluoride. FARBWERKE HOECHST A.G. 6 Dec., 1966, No. 54553/66. Heading B1L. [Also in Division C1A] Mixtures of HC1 and HF gases are separated by scrubbing the gaseous mixture with concentrated hydrochloric acid in countercurrent flow in a cascade arrangement in which mixing of the components between individual stages is minimized, suitably a valve tray, a slotted tray, or a bubble cap column having preferably 10-30 trays. The scrubbing is best conducted at (below 50‹C., and preferably at -20 to 20‹C., although it may be carried out below -35‹C., provided that formation of solid phase is avoided; the pressure in the scrubbing process may be atmospheric to 5 atmospheres gauge, but is preferably less than 3 atmospheres gauge. Water is introduced to the scrubbing column either as such or in the concentrated hydrochloric acid in an amount of at least 5 g., and preferably 20-120 g., per mole of HF to be absorbed; the hydrochloric acid used for scrubbing is suitably obtamed by adiabatically absorbing the HCl gas from which the HF has been scrubbed in water, and is suitably of 32-45% strength. The gas mixtures so treated may also contain inert, water insoluble substances such as hydrogen, nitrogen, oxygen, chlorine, hydrocarbons, or halogenated derivatives of hydrocarbons, but the process is particularly applicable to gas mixtures obtained by fluorinating chlorinated hydrocarbons having 1-4 carbon atoms. Such gas streams are preferably first passed in 1-60 seconds through a bed of active carbon at ambient temperature to 200‹C., 'and 1-10 atmospheres in the presence of 1-100 g. steam/m<SP>3</SP>crude gas, the steam used in such treatment suitably being added in the form of aqueous HCl or HF obtained as bottoms in the subsequent scrubbing column to which the pre-treated gas stream then passes. |
