Abstract: By using a simulation device of CO₂ circulation purification in a closed environment, CO₂ circulation purification experiments were carried out with three kinds of solid chemical absorbents, LiOH, Ca(OH) 2 and soda lime. Experimental results show that all the absorbents can absorb CO₂, and there are the optimal space velocity values for the three absorbents, which are 110400, 38700, and 40500 h^-1, respectively. Under these space velocity value conditions, the reaction time is the shortest and the reaction rate is the fastest for absorbing the CO₂ volume fraction of 2% to 0.03%. The relationships between reaction rate and CO₂ mass concentration as well as the maximum reaction rate order of the three absorbents under experimental conditions were obtained by function fitting and mathematical analysis. Further analysis indicates that the CO₂ absorption rates of the three absorbents under the optimal space velocity value conditions are able to meet the requirements of relevant standards for actual CO₂ purification in closed environments, while the CO₂ volume fraction would fluctuate around certain intermediate values in theory.