Kinetic study of CO2 capture on ternary nitrates modified MgO with different precursor and morphology

Abstract

• Different morphologies of MgO samples were synthesized. • Ternary nitrates were used to promote the CO 2 adsorption performance of MgO. • The kinetic of MgO derived adsorbents for CO 2 adsorption were analyzed. • The adsorption mechanisms of MgO derived adsorbents were discussed. In this paper, the magnesium chloride hexahydrate (MgCl 2 ·6H 2 O), magnesium nitrate hexahydrate (Mg(NO 3 ) 2 ·6H 2 O) and magnesium hydroxide (Mg(OH) 2 ) were used as precursors to synthesize different morphologies of MgO by hydrothermal method and precipitation method. Ternary nitrates [TNO 3 ] were invited to promote the CO 2 capture performance of the synthesized MgO samples. It demonstrated that different precursor and morphology may influence the specific surface area of the MgO, thus influence the optimized loading amount of TNO 3 . The MgO sample fabricated with Mg(NO 3 ) 2 ·6H 2 O as precursor and potassium carbonate (K 2 CO 3 ) as precipitator showed the rod like morphology with the largest specific surface area, which CO 2 capture capacity can reach 10.48 mmol g −1 in 30 min and get the maximum value of 13.45 mmol g −1 in 240 min in pure CO 2 at 300 °C with loading of 20 mol% TNO 3 . In addition, the Pseudo-first order (PFO) model, Pseudo-second order (PSO) model, Boyd kinetic (BK) model, and Intra-particle diffusion (IPD) model were proposed to investigate the limiting factors and adsorption behavior of MgO derived CO 2 adsorbent. At last, the adsorption mechanisms of MgO derived CO 2 adsorbent with or without TNO 3 loading were discussed.