Alkalized alumina can be used for the removal of sulfur dioxide from stack gases. Before the pellets are recycled to the sorption section, they must be regenerated with a reducing gas. Several practical alternatives for regeneration are possible, resulting in single- and multiple-stage mechanisms. Besides the reduction itself, consideration is given to side reactions that can have a deleterious effect on the ability of the sorbent to be reused, its ease of regeneration, and its physical properties. Data were obtained from a bench-scale system designed to study the mechanism and kinetics of the reactions. Regeneration can be accomplished at 600 deg to 700 deg c with hydrogen, carbon monoxide, and their mixtures. When carbon monoxide is used, some of the sulfate is reduced to the sulfide and a second-stage reaction with carbon dioxide is needed to complete regeneration to the reactive oxide. Data from this and other research are being used for the design of a prototype sulfur dioxide-removal plant.
Chem. Eng. Symp. Ser., V. 67, No. 115, PP. 46-51