In a fixed-bed absorber at 40 degreesC, the dynamics of carbon dioxide sorption over composite sorbents prepared by impregnation of potassium carbonate in various porous matrixes is studied. The dynamic capacity of the synthesized sorbents is shown to reach 0.12 g CO2 per 1 g of the sorbent. The composite dynamic capacity depends on the nature of the host matrix and decreases in the sequence alumina > activated carbon > vermiculite > silica gel. For K2CO3-on-alumina, the sorption capacity decreases considerably after the first cycle of "absorption and regeneration under 200-350 degreesC", whereas the sorbents based on active carbons could be reversibly restored. The findings are discussed within the idea on a chemical interaction between the host matrix and the impregnated salt.