Carbon Dioxide Reduction with Alkali-Metal Amalgams

摘要

The reduction of carbon dioxide by alkali-metal amalgams was studied as a potential means for reclamation of carbon dioxide waste gas in space systems. The carbon dioxide reduction reactions were investigated at moderate temperatures and pressures - typically 25 to 200 C and 1 to 1.1 atmospheres. The investigations demonstrated that carbon dioxide can be reduced effectively by an appropriate alkali-metal amalgam system. Moreover, the alkali-amalgam expended in the carbon dioxide reduction process can be reclaimed by electrolysis from an aqueous or nonaqueous salt solution containing the fixed carbon dioxide products. The carbon dioxide fixation products can be drained-off or, in some cases, recycled for further reduction. In the carbon dioxide reduction reactions by alkali-amalgam systems, a wide variety of products ranging from simple organic acids, such as formic and oxalic acid, to totally reduced carbon dioxide in the form of carbon black have been identified. The types of products formed are dependent upon such factors as the type of alkali-metal amalgam used, temperature, pressure, and electrolytic reducing conditions. In electrolytic recovery of the alkali-metal amalgam from aqueous media, oxygen also is produced as a useful by-product of the carbon dioxide reduction system. (Author)