A soft-chemistry route has been used for preparation of pure and promoted nanocrystalline lithium zirconate with different stoichiometries. The objective of this investigation has been to study the effect of different compositions on the acceptor and optimize the working properties of lithium zirconate. Special attention has been given to study the effect of different Li2O-ZrO2 stoichiometries on the CO2 capture rates. In addition, the partial substitution of Li2O with K2O as a promoter has been addressed. It has been found that both the capture rate and capacity of lithium zirconate depend considerably on the Li2O to ZrO2 ratio. Enhanced capture rates are observed when a deficiency of Li2O is introduced. It is believed that the excess ZrO2 might act as a dispersant and introduce more reactive boundaries. Moreover, the addition of K2O results also in improved capture rates due to the presence of molten carbonates, but lower capacities and poorer stability due to particle coarsening. The present of free ZrO2 seems also beneficial for the stability of K2O-doped acceptors. Therefore, controlling the K:Li:Zr ratio has been found to be crucial for tailoring the properties of lithium zirconate. An optimized composition can result in an acceptor with enhanced capture rates, stability, and higher degree of utilization.