Removal of hydrogen fluoride from gaseous mixtures of hydrogen fluoride and hydrogen chloride

摘要

A method of removing hydrogen fluoride from gaseous mixtures of hydrogen fluoride and hydrogen chloride, which contain up to about 5 percent by weight of hydrogen fluoride, is described. The method comprises initially contacting the gaseous mixture with a particulate, substantially anhydrous, bed of alkaline earth metal chloride material, for example, calcium chloride, to produce an effluent gas mixture having a substantially reduced hydrogen fluoride content. The effluent gas is then contacted with a secondary treatment bed of particulate, substantially anhydrous, alkaline earth metal chloride material, for example, calcium chloride, to produce a product gas containing less than 20 ppm of hydrogen fluoride. The temperature of the secondary treatment bed is maintained in the range from about -20° to about + 20° C., and, more preferably, in the range from about 0° to about 5. degree. C. The temperature of the secondary treatment bed may be controlled by control of the amount of hydrogen fluoride in the gas mixture entering the secondary treatment bed and by the use of an intervening gas cooling step.