Influence of NOx and SO2 on Li4SiO4 based carbon capture

Puccini et al. [82] performed CO₂ absorption tests in an atmosphere of 4 vol.% CO₂ and various concentrations of NO, and the results showed that NO in the absorption atmosphere does not show a harmful effect on the CO₂ absorption capacity of Li₄SiO₄ material. Furthermore, when the concentration of SO₂ in the absorption atmosphere increased from 0 to 2000 ppm, the weight change of Li₄SiO₄ material increased with the increase of SO₂ concentration, but the regeneration performance of Li₄SiO₄ material in the presence of SO₂ was worse compared with that in the absence of SO₂. Additionally, the cyclic CO₂ absorption performance of Li₄SiO₄ material was negatively influenced in the presence of SO₂ under absorption and regeneration atmospheres [71]. The authors ascribed this phenomenon to the nonreversible reaction between SO₂ and Li₄SiO₄, as shown in Equations (12) and (13):

The formation of Li₂SO₃ and Li₂SO₄ prevented the regeneration of the materials, indicating that the presence of SO₂ in the absorption atmosphere has an adverse effect on the absorption performance of Li₄SiO₄ material [82]. In general, NO had no negative impact on the CO₂ absorption property of Li₄SiO₄ materials, while SO₂ had an adverse effect due to the formation of the irreversible Li₂SO₃ and Li₂SO₄, so SO₂ must be scrubbed prior to the trapping of CO₂. However, the exact joint role and acting mechanism of NO and SO₂ in the process of CO₂ capture are still unknown, and the effects of other contaminants, like HCl or H₂S, on the CO₂ absorption by Li₄SiO₄ material are not clear, thus further research is necessary. “