High temperature adsorption of CO2 on various hydrotalcite-like compounds

A study was conducted to describe and quantify how substitution of the divalent cation and interlayer charge compensating anions affect the CO(2) adsorptive capacity of various hydrotalcite-like compounds (HTlcs). Physical and chemical properties of the HTlcs were evaluated using a number of methods and the CO(2) adsorption rate and capacity were measured at elevated temperature (603 K). The results showed that the synthetic analogue of the naturally occurring hydrotalcite mineral, [Mg(0.73)Al(0.27)(OH)(2)](CO(3))(0.13)center dot H(2)O, had the best overall adsorption capacity and kinetics. The stability of the adsorption capacity was tested by subjecting the model HTlc to 10 equilibrium adsorption and desorption cycles. At the end of the cycle, the HTlc had maintained approximately sixty-five percent of its initial capacity. Temperature programmed desorption of CO(2) was used to quantify the surface basicity of the various HTlcs. The results showed that the reversible physisorption portion of the CO(2) isotherm was correlated to the number of surface basic sites on the HTlcs.