Kinetic study and modeling of the high temperature CO2 capture by Na2ZrO3 solid absorbent

Hydrogen production through sorption enhanced reforming (SER) use a solid CO2 absorbent to increase hydrogen purity (98%) and to perform reforming and WGS reactions in one single step, thus producing high methane conversions and important energy savings. Na2ZrO3 is as an alternate synthetic CO2 solid absorbent for SER applications. The present research is aimed to establish CO2 sorption kinetics parameters; reaction order, rate constant, apparent, intrinsic and diffusional activation energies. Na2ZrO3 sorption kinetics was studied through TGA as a function of CO2 concentration and temperature. A global reaction rate of first order in CO2 and a strong dependence in temperature was found. The approximate solution to the shrinking core model was used to fit the data. Modeling results indicated the surface reaction as the main resistance to the reaction rate, controlling reaction kinetics with only a minor contribution of the product layer diffusion resistance toward the end of the reaction.

► Global rate for CO2 absorption by Na2ZrO3 was first order.
► Intrinsic and product layer diffusional activation energies govern the reaction.
► The surface reaction is controlling the reaction kinetics.
► Na2ZrO3 exhibits the fastest reaction kinetics among synthetic CO2 absorbents.